Slurry coating method for making batteries

ABSTRACT

A method of making a battery (preferably, an IMD battery) that includes applying a cathode material slurry that includes an active cathode material, a binder, an optional thickener and/or an optional dispersant, and a solvent to at least one major surface of a current collector.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 61/297,808, filed on Jan. 24, 2010, which isincorporated herein by reference.

BACKGROUND

A wide variety of implantable medical devices (IMDs) for delivering atherapy and/or monitoring a physiologic condition have been clinicallyimplanted or proposed for clinical implantation in patients. Someimplantable medical devices may employ one or more elongated electricalleads and/or sensors. Such implantable medical devices may delivertherapy or monitor the heart, muscle, nerve, brain, stomach or otherorgans. In some cases, implantable medical devices deliver electricalstimulation therapy and/or monitor physiological signals via one or moreelectrodes or sensor elements, which may be included as part of one ormore elongated implantable medical leads. Implantable medical leads maybe configured to allow electrodes or sensors to be positioned at desiredlocations for delivery of stimulation or sensing. For example,electrodes or sensors may be located at a distal portion of the lead. Aproximal portion of the lead may be coupled to an implantable medicaldevice housing, which may contain electronic circuitry such asstimulation generation and/or sensing circuitry.

For example, implantable medical devices, such as cardiac pacemakers orimplantable cardioverter defibrillators (ICDs), provide therapeuticstimulation to the heart by delivering electrical therapy signals suchas pacing pulses, or cardioversion or defibrillation shocks, viaelectrodes of one or more implantable leads. In some cases, such animplantable medical device may sense intrinsic depolarizations of theheart, and control the delivery of such signals to the heart based onthe sensing. When an abnormal rhythm is detected, such as bradycardia,tachycardia or fibrillation, an appropriate electrical signal or signals(e.g., in the form of pulses) may be delivered to restore the normalrhythm. For example, in some cases, an implantable medical device maydeliver pacing, cardioversion or defibrillation signals to the heart ofthe patient upon detecting ventricular tachycardia, and delivercardioversion or defibrillation electrical signals to a patient's heartupon detecting ventricular fibrillation.

Also, implantable medical devices, such as electrical stimulators ortherapeutic agent delivery devices, may be used in different therapeuticapplications, such as deep brain stimulation (DBS), spinal cordstimulation (SCS), pelvic stimulation, gastric stimulation, peripheralnerve stimulation or delivery of a pharmaceutical agent, insulin, a painrelieving agent, or an anti-inflammatory agent to a target tissue sitewithin a patient. A medical device may be used to deliver therapy to apatient to treat a variety of symptoms or patient conditions such aschronic pain, tremors, Parkinson's disease, other types of movementdisorders, seizure disorders (e.g., epilepsy), urinary or fecalincontinence, sexual dysfunction, obesity, mood disorders, gastroparesisor diabetes. In some cases, the electrical stimulation may be used formuscle stimulation, e.g., functional electrical stimulation (FES) topromote muscle movement or prevent atrophy. In some therapy systems, animplantable electrical stimulator delivers electrical therapy to atarget tissue site within a patient with the aid of one or more medicalleads that include electrodes. In addition to or instead of electricalstimulation therapy, a medical device may deliver a therapeutic agent toa target tissue site within a patient with the aid of one or more fluiddelivery elements, such as a catheter.

SUMMARY

The present disclosure is directed to implantable medical devices,implantable medical device systems that include such implantable medicaldevices, and implantable medical device batteries, as well as methods ofmaking. Such devices can include a battery of relatively small volumebut of relatively high power (reported as therapeutic power) andrelatively high capacity (reported as capacity density), although thisis not a requirement of all embodiments of the present disclosure.

In one embodiment, the present disclosure provides a method of making abattery (preferably, an IMD battery), the method comprising: preparing acathode material slurry comprising an active cathode material, a binder,an optional thickener and/or an optional dispersant, and a solvent;applying the cathode material slurry to at least one major surface of acurrent collector; removing the solvent from the coated cathode slurrymaterial to form a dry cathode coating; compressing the dry cathodecoating to reduce porosity and thickness of the coating; and combiningthe cathode with an anode, one or more separators, and an electrolyte toform a battery. Preferably, the cathode material slurry comprisesfibrous particles, and even more preferably a mixture of fibrousparticles with irregularly shaped agglomerates of needle-shapedparticles.

Such slurry coating method can be used in making a cathode of a batteryof relatively small volume but of relatively high power (reported astherapeutic power) and relatively high capacity (reported as capacitydensity). Preferably, the slurry includes a binder comprisingstyrene-butadiene rubber. Thus, the slurry coating method describedherein can be used to make the following embodiments.

In one embodiment, the present disclosure provides an implantablecardioverter defibrillator device comprising: control electronics fordelivering therapy and/or monitoring physiological signals, the controlelectronics comprising: a processor; memory; a stimulation generatorthat generates at least one of cardiac pacing pulses, defibrillationshocks, and cardioversion shocks; and a sensing module for monitoring apatient's heart rhythm; one or more defibrillator capacitors; and

an implantable medical device battery operably connected to the controlelectronics to deliver power to the control electronics, and operablyconnected to the capacitors to charge the capacitors (although thebattery is not directly connected to the capacitors, it is connected toa charging circuit, thereby being operably connected to the capacitors);wherein the battery has a total volume of no greater than 6.0 cubiccentimeters (cc), the battery comprising: an anode comprising lithium; acathode having a total uniform thickness of less than 0.014 inch; aseparator between the anode and the cathode; and an electrolytecontacting the anode, the cathode, and the separator; wherein thecathode material comprises a metal oxide; wherein the battery has atherapeutic power of at least 0.11 watt (W) for every joule oftherapeutic energy delivered over the useful life of the battery, and atherapeutic capacity density of at least 0.08 ampere hour per cubiccentimeter (Ah/cc).

In another embodiment, the present disclosure provides an implantablemedical device comprising: control electronics for delivering therapyand/or monitoring physiological signals, the control electronicscomprising: a processor; and memory; and an implantable medical devicebattery operably connected to the control electronics to deliver powerto the control electronics; wherein the battery has a total volume of nogreater than 6.0 cc, the battery comprising: an anode comprisinglithium; a cathode having a total uniform thickness of less than 0.014inch; a separator between the anode and the cathode; and an electrolytecontacting the anode, the cathode, and the separator; wherein thecathode material comprises a metal oxide; wherein the battery has atherapeutic power of at least 0.11 W for every joule of therapeuticenergy delivered over the useful life of the battery, and a therapeuticcapacity density of at least 0.08 Ah/cc.

In another embodiment, the present disclosure also provides animplantable medical device comprising: control electronics fordelivering therapy and/or monitoring physiological signals, the controlelectronics comprising: a processor; and memory; and an implantablemedical device battery operably connected to the control electronics todeliver power to the control electronics; wherein the battery has atotal volume of no greater than 6.0 cc, the battery comprising: an anodecomprising lithium; a cathode comprising a single current collector(e.g., in any one cathode plate) and having a total uniform thickness ofless than 0.014 inch; a separator between the anode and the cathode; andan electrolyte contacting the anode, the cathode, and the separator;wherein the cathode material comprises a layer on each major surface ofthe single current collector, wherein the layer comprises a mixturecomprising a metal oxide and carbon monofluoride; wherein the batteryhas a therapeutic power of at least 0.11 W for every joule oftherapeutic energy delivered over the useful life of the battery, and atherapeutic capacity density of at least 0.08 Ah/cc.

The present disclosure also provides an implantable medical devicesystem comprising: an implantable medical device as described above; and

components operably attached to the implantable medical device fordelivering therapy and/or monitoring physiological signals.

The present disclosure also provides an implantable medical devicebattery comprising: an anode comprising lithium; a cathode having atotal uniform thickness of less than 0.014 inch; wherein the cathodematerial comprises a metal oxide; a separator between the anode and thecathode; and an electrolyte contacting the anode, the cathode, and theseparator; wherein the battery has a therapeutic power of at least 0.11W for every joule of therapeutic energy delivered over the useful lifeof the battery, and a therapeutic capacity density of at least 0.08Ah/cc.

In certain embodiments of the present disclosure, the battery volume ispreferably no greater than 5.0 cc. Typically, in such devices thebattery volume is at least 3.0 cc.

In certain embodiments of the present disclosure, the therapeutic powerof the battery is at least 0.14 W for every joule of therapeutic energydelivered over the useful life of the battery.

In certain embodiments of the present disclosure, the therapeuticcapacity density of the battery is at least 0.10 Ah/cc.

In certain embodiments of the present disclosure, the surface area ofeach of the cathode and anode is at least 60 cm².

In certain embodiments of the present disclosure, the cathode comprisesa silver vanadium oxide. In certain embodiments, the cathode comprises amixture of two or more materials (particularly, a mixture of a silvervanadium oxide and carbon monofluoride).

In certain embodiments of the implantable devices of the presentdisclosure, the cathode comprises a single current collector (e.g., inany one cathode plate of a stacked cathode).

The present disclosure also provides a non-rechargeable batterycomprising: an anode; a cathode comprising a binder comprisingstyrene-butadiene rubber; a separator between the anode and the cathode;and an electrolyte contacting the anode, the cathode, and the separator.This battery may be of relatively small volume but of relatively highpower (reported as therapeutic power) and relatively high capacity(reported as capacity density).

The term “components for delivering therapy and/or monitoringphysiological signals” refers to components of an IMD system thatdeliver electrical stimulation therapy (e.g., functional electricalstimulation to promote muscle movement, or stimulation to the heartusing pacing pulses, cardioversion or defibrillation shocks), deliver atherapeutic agent, monitor physiological signals (e.g., detectventricular fibrillation), or both deliver and monitor (e.g., detecttachycardia and deliver electrical signals to restore normal rhythm tothe heart).

The term “total volume” in the context of battery volume refers to thetotal overall volume of the battery, not the volume of any individualcell. Although a battery may include one or more individual cells, eachof which includes a cathode, anode, separator, and an electrolyte, thetotal volume is the summation of the volumes of the individual cells.

The term “total uniform thickness” in the context of an electrode refersto the total overall thickness of the electrode, not the thickness ofany individual layer (e.g., a layer of cathode material or a layer ofmetal foil used as a current collector) if the electrode is a layeredconstruction. Furthermore, this thickness is uniform along its length(excluding any uncoated areas such as tabs or edges on individualelectrode plates and the portions of the electrode forming the outermostwraps or plates), with tolerances of no more than ±0.003 inch (3 mil),and preferably no more than ±0.001 inch (1 mil).

The term “surface area” in the context of an electrode refers to thetotal area of the electrode (e.g., the area of the active cathodematerial, which excludes any areas such as tabs or edges, for example,on individual cathode plates that do not include cathode material)excluding any area that is not opposing the other electrode. Forexample, the surface area of a stacked plate electrode is the summationof the surface areas of the individual electrode plates joinedelectrically to form one electrode but does not include the outermostsurface of the two electrode plates at each end of the stack.

The term “therapeutic capacity” refers to the total capacity delivereduntil the cell power decreases to a specified wattage. In this context,the “cell power” is the average voltage times the average current, andthe “specified wattage” is defined when the average voltage=1.6 Volts(V). This “therapeutic capacity” differs from anode capacity, cathodecapacity, and cell capacity as traditionally used in discussions ofbatteries, in that the latter teal's all refer to complete discharge ofthe respective components.

The term “therapeutic capacity density” refers to the battery'stherapeutic capacity delivered over the useful life of the batterydivided by the battery volume.

The term “useful life” in the context of the battery life refers to thelongevity that is typical for conventional implantable medical devicebatteries, which is on the order of years. Preferably, the useful lifeis at least 5 years.

The term “therapeutic power” refers to the amount of cell power (definedabove in the context of therapeutic capacity) a battery delivers forevery joule of therapeutic energy delivered. In this context,“therapeutic energy” is the amount of energy delivered by a stimulationgenerator to a patient in a single stimulation event. Examples of suchan event include pacing, cardioversion, and defibrillation. A “single”event is, for example, one pacing shock, one defibrillation shock, orone cardioversion shock.

The term “particle size” refers to the longest dimension of a particle.For a spherical particle, this is the diameter.

The terms “comprises” and variations thereof do not have a limitingmeaning where these terms appear in the description and claims.

The terms “preferred” and “preferably” refer to embodiments of thedisclosure that may afford certain benefits, under certaincircumstances. However, other embodiments may also be preferred, underthe same or other circumstances. Furthermore, the recitation of one ormore preferred embodiments does not imply that other embodiments are notuseful, and is not intended to exclude other embodiments from the scopeof the disclosure.

As used herein, “a,” “an,” “the,” “at least one,” and “one or more” areused interchangeably. Thus, for example, a device that comprises “a”capacitors can be interpreted to mean that the device includes “one ormore” capacitors.

As used herein, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise. Theterm “and/or” means one or all of the listed elements or a combinationof any two or more of the listed elements (e.g., delivering therapyand/or monitoring physiological signals means delivering therapy,monitoring physiological conditions, or doing both monitoring anddelivering).

Also herein, all numbers are assumed to be modified by the teem “about”and preferably by the term “exactly.” Notwithstanding that the numericalranges and parameters setting forth the broad scope of the disclosureare approximations, the numerical values set forth in the specificexamples are reported as precisely as possible. All numerical value,however, inherently contain certain errors necessarily resulting fromthe standard deviation found in their respective testing measurements.

Also herein, the recitations of numerical ranges by endpoints includeall numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, 5, etc.).

The above summary of the present disclosure is not intended to describeeach disclosed embodiment or every implementation of the presentdisclosure. The description that follows more particularly exemplifiesillustrative embodiments. In several places throughout the application,guidance is provided through lists of examples, which examples can beused in various combinations. In each instance, the recited list servesonly as a representative group and should not be interpreted as anexclusive list.

BRIEF DESCRIPTION OF FIGURES

The figures presented herein are idealized, not to scale, and areintended to be merely illustrative and non-limiting.

FIG. 1 is a conceptual diagram illustrating an exemplary implantablemedical device system (e.g., a therapy system) of the presentdisclosure.

FIG. 2 is a conceptual diagram illustrating an IMD and leads of atherapy system of the present disclosure in greater detail.

FIG. 3 is a conceptual diagram illustrating another example of animplantable medical device system (e.g., a therapy system) of thepresent disclosure.

FIG. 4 provides further detail of an exemplary IMD of the presentdisclosure.

FIG. 5 is block diagram of an exemplary programmer used with animplantable medical device of the present disclosure.

FIG. 6 is a block diagram illustrating a system that includes anexternal device, such as a server, and one or more computing devicescoupled to an IMD of the present disclosure, and a programmer via anetwork 196.

FIG. 7A is a conceptual diagram illustrating an exemplary implantablemedical device system (e.g., a therapy system) that provides electricalstimulation therapy to a patient according to the present disclosure.

FIG. 7B is a conceptual diagram of another example of an implantablemedical device system (e.g., therapy system) that delivers electricalstimulation to target tissue sites proximate to the spine of a patientaccording to the present disclosure.

FIG. 8 is a functional block diagram of an exemplary IMD of the presentdisclosure.

FIG. 9 is a functional block diagram of an exemplary programmer usedwith an IMD of the present disclosure.

FIG. 10 is a cutaway perspective view of an IMD of the presentdisclosure.

FIG. 11 is a cutaway perspective view of a battery in the IMD of FIG.10.

FIG. 12 is an enlarged view of a portion of the battery depicted in FIG.11 and designated by line 212.

FIG. 13-16 are graphs of therapeutic capacity density relative to cellvolumes for various batteries having various therapeutic powercapabilities.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present disclosure is directed to implantable medical devices,implantable medical device systems that include such implantable medicaldevices, and implantable medical device batteries, as well as methods ofmaking. Such devices can include a battery of relatively small volumebut of relatively high power (reported as therapeutic power) andrelatively high capacity (reported as capacity density), althoughvarious embodiments of the present invention do not require a battery ofrelatively small volume, relatively high power, and relatively highcapacity (reported as capacity density). A wide variety of implantablemedical devices (IMDs) for delivering a therapy and/or monitoring aphysiologic condition have been clinically implanted or proposed forclinical implantation in patients. Exemplary such IMDs includeimplantable pulse generators (IPGs), implantable cardioverterdefibrillators (ICDs), neurostimulators, or other suitable devices. Ofparticular importance are implantable cardioverter defibrillators(ICDs).

Whether for electrical stimulation therapy, delivering a therapeuticagent, and/or monitoring a physiological condition, for certainembodiments of the present disclosure it is desirable to reduce IMDbattery volumes for both patient comfort and aesthetics, whilemaintaining relatively high power capability and capacity.

Exemplary Implantable Medical Devices and Systems

FIG. 1 is a conceptual diagram illustrating an exemplary implantablemedical device system (e.g., a therapy system) 10 that may be used toprovide therapy to heart 12 of patient 14. Patient 14 ordinarily, butnot necessarily, will be a human. Therapy system 10 includes IMD 16,which is coupled to leads 18, 20, 22, and programmer 24. IMD 16 may be,for example, an implantable pacemaker, cardioverter, and/ordefibrillator that provides electrical signals to heart 12 viaelectrodes coupled to one or more of leads 18, 20, and 22.

Leads 18, 20, 22 extend into the heart 12 of patient 14 to senseelectrical activity of heart 12 and/or deliver electrical stimulation toheart 12. In the example shown in FIG. 1, right ventricular (RV) lead 18extends through one or more veins (not shown), the superior vena cava(not shown), and right atrium 26, and into right ventricle 28. Leftventricular (LV) coronary sinus lead 20 extends through one or moreveins, the vena cava, right atrium 26, and into the coronary sinus 30 toa region adjacent to the free wall of left ventricle 32 of heart 12.Right atrial (RA) lead 22 extends through one or more veins and the venacava, and into the right atrium 26 of heart 12.

IMD 16 may sense electrical signals attendant to the depolarization andrepolarization of heart 12 via electrodes (not shown in FIG. 1) coupledto at least one of the leads 18, 20, 22. In some examples, IMD 16provides pacing pulses to heart 12 based on the electrical signalssensed within heart 12. The configurations of electrodes used by IMD 16for sensing and pacing may be unipolar or bipolar. IMD 16 may alsoprovide defibrillation therapy and/or cardioversion therapy viaelectrodes located on at least one of the leads 18, 20, 22. IMD 16 maydetect arrhythmia of heart 12, such as fibrillation of ventricles 28 and32, and deliver defibrillation therapy to heart 12 in the form ofelectrical pulses. In some examples, IMD 16 may be programmed to delivera progression of therapies, e.g., pulses with increasing energy levels,until a fibrillation of heart 12 is stopped. IMD 16 detects fibrillationby employing one or more fibrillation detection techniques known in theart.

In some examples, programmer 24 may be a handheld computing device or acomputer workstation. Programmer 24 may include a user interface thatreceives input from a user. The user interface may include, for example,a keypad and a display, which may, for example, be a cathode ray tube(CRT) display, a liquid crystal display (LCD) or light emitting diode(LED) display. The keypad may take the form of an alphanumeric keypad ora reduced set of keys associated with particular functions. Programmer24 can additionally or alternatively include a peripheral pointingdevice, such as a mouse, via which a user may interact with the userinterface. In some embodiments, a display of programmer 24 may include atouch screen display, and a user may interact with programmer 24 via thedisplay.

A user, such as a physician, technician, or other clinician, mayinteract with programmer 24 to communicate with IMD 16. For example, theuser may interact with programmer 24 to retrieve physiological ordiagnostic information from IMD 16. A user may also interact withprogrammer 24 to program IMD 16, e.g., select values for operationalparameters of the IMD.

For example, the user may use programmer 24 to retrieve information fromIMD 16 regarding the rhythm of heart 12, trends therein over time, ortachyarrhythmia episodes. As another example, the user may useprogrammer 24 to retrieve information from IMD 16 regarding other sensedphysiological parameters of patient 14, such as intracardiac orintravascular pressure, activity, posture, respiration, or thoracicimpedance. As another example, the user may use programmer 24 toretrieve information from IMD 16 regarding the performance or integrityof IMD 16 or other components of system 10, such as leads 18, 20, and22, or a power source of IMD 16.

The user may use programmer 24 to program a therapy progression, selectelectrodes used to deliver defibrillation shocks, select waveforms forthe defibrillation shock, or select or configure a fibrillationdetection algorithm for IMD 16. The user may also use programmer 24 toprogram aspects of other therapies provided by IMD 16, such ascardioversion or pacing therapies. In some examples, the user mayactivate certain features of IMD 16 by entering a single command viaprogrammer 24, such as depression of a single key or combination of keysof a keypad or a single point-and-select action with a pointing device.

IMD 16 and programmer 24 may communicate via wireless communicationusing any techniques known in the art. Examples of communicationtechniques may include, for example, low frequency or radio frequency(RF) telemetry, but other techniques are also contemplated. In someexamples, programmer 24 may include a programming head that may beplaced proximate to the patient's body near the IMD 16 implant site inorder to improve the quality or security of communication between IMD 16and programmer 24.

FIG. 2 is a conceptual diagram illustrating IMD 16 and leads 18, 20, 22of therapy system 10 in greater detail. Leads 18, 20, 22 may beelectrically coupled to a stimulation generator, a sensing module, orother modules MD 16 via connector block 34. In some examples, proximalends of leads 18, 20, 22 may include electrical contacts thatelectrically couple to respective electrical contacts within connectorblock 34. In addition, in some examples, leads 18, 20, 22 may bemechanically coupled to connector block 34 with the aid of set screws,connection pins, or another suitable mechanical coupling mechanism.

Each of the leads 18, 20, 22 includes an elongated insulative lead body,which may carry a number of concentric coiled conductors separated fromone another by tubular insulative sheaths. In the illustrated example, apressure sensor 38 and bipolar electrodes 40 and 42 are locatedproximate to a distal end of lead 18. In addition, bipolar electrodes 44and 46 are located proximate to a distal end of lead 20 and bipolarelectrodes 48 and 50 are located proximate to a distal end of lead 22.In FIG. 2, pressure sensor 38 is disposed in right ventricle 28.Pressure sensor 30 may respond to an absolute pressure inside rightventricle 28, and may be, for example, a capacitive or piezoelectricabsolute pressure sensor. In other examples, pressure sensor 30 may bepositioned within other regions of heart 12 and may monitor pressurewithin one or more of the other regions of heart 12, or may bepositioned elsewhere within or proximate to the cardiovascular system ofa patient to monitor cardiovascular pressure associated with mechanicalcontraction of the heart.

Electrodes 40, 44 and 48 may take the form of ring electrodes, andelectrodes 42, 46 and 50 may take the form of extendable helix tipelectrodes mounted retractably within insulative electrode heads 52, 54and 56, respectively. Each of the electrodes 40, 42, 44, 46, 48 and 50may be electrically coupled to a respective one of the coiled conductorswithin the lead body of its associated lead 18, 20, 22, and therebycoupled to respective one of the electrical contacts on the proximal endof leads 18, 20, 22.

Electrodes 40, 42, 44, 46, 48 and 50 may sense electrical signalsattendant to the depolarization and repolarization of heart 12. Theelectrical signals are conducted to IMD 16 via the respective leads 18,20, 22. In some examples, IMD 16 also delivers pacing pulses viaelectrodes 40, 42, 44, 46, 48 and 50 to cause depolarization of cardiactissue of heart 12. In some examples, as illustrated in FIG. 2, IMD 16includes one or more housing electrodes, such as housing electrode 58,which may be formed integrally with an outer surface ofhermetically-sealed housing 60 of IMD 16 or otherwise coupled to housing60. In some examples, housing electrode 58 is defined by an uninsulatedportion of an outward facing portion of housing 60 of IMD 16. Otherdivision between insulated and uninsulated portions of housing 60 may beemployed to define two or more housing electrodes. In some examples,housing electrode 58 comprises substantially all of housing 60. Any ofthe electrodes 40, 42, 44, 46, 48 and 50 may be used for unipolarsensing or pacing in combination with housing electrode 58.

As described with reference to FIG. 4, housing 60 may enclose astimulation generator that generates cardiac pacing pulses and/ordefibrillation and/or cardioversion shocks, as well as a sensing modulefor monitoring the patient's heart rhythm.

Leads 18, 20, 22 also include elongated electrodes 62, 64, 66,respectively, which may take the form of a coil. IMD 16 may deliverdefibrillation shocks to heart 12 via any combination of elongatedelectrodes 62, 64, 66, and housing electrode 58. Electrodes 58, 62, 64,66 may also be used to deliver cardioversion pulses to heart 12.Electrodes 62, 64, 66 may be fabricated from any suitable electricallyconductive material, such as, but not limited to, platinum, platinumalloy or other materials known to be usable in implantabledefibrillation electrodes.

Pressure sensor 38 may be coupled to one or more coiled conductorswithin lead 18. In FIG. 2, pressure sensor 38 is located more distallyon lead 18 than elongated electrode 62. In other examples, pressuresensor 38 may be positioned more proximally than elongated electrode 62,rather than distal to electrode 62. Further, pressure sensor 38 may becoupled to another one of the leads 20, 22 in other examples, or to alead other than leads 18, 20, 22 carrying stimulation and senseelectrodes. In addition, in some examples, pressure sensor 38 may beself-contained device that is implanted within heart 12, such as withinthe septum separating right ventricle 28 from left ventricle 32, or theseptum separating right atrium 26 from left atrium 33. In such anexample, pressure sensor 38 may wirelessly communicate with IMD 16.

The configuration of therapy system 10 illustrated in FIGS. 1 and 2 ismerely one example. In other examples, a therapy system may includeepicardial leads and/or patch electrodes instead of or in addition tothe transvenous leads 18, 20, 22 illustrated in FIG. 1. Further, IMD 16need not be implanted within patient 14. In examples in which IMD 16 isnot implanted in patient 14, IMD 16 may deliver defibrillation shocksand other therapies to heart 12 via percutaneous leads that extendthrough the skin of patient 14 to a variety of positions within oroutside of heart 12.

In other examples of therapy systems that provide electrical stimulationtherapy to heart 12, a therapy system may include any suitable number ofleads coupled to IMD 16, and each of the leads may extend to anylocation within or proximate to heart 12. For example, other examples oftherapy systems may include three transvenous leads located asillustrated in FIGS. 1 and 2, and an additional lead located within orproximate to left atrium 33. As another example, other examples oftherapy systems may include a single lead that extends from IMD 16 intoright atrium 26 or right ventricle 28, or two leads that extend into arespective one of the right ventricle 28 and right atrium 26. An exampleof this type of therapy system is shown in FIG. 3.

FIG. 3 is a conceptual diagram illustrating another example of animplantable medical device system (e.g., a therapy system) 70, which issimilar to therapy system 10 of FIGS. 1-2, but includes two leads 18,22, rather than three leads. Leads 18, 22 are implanted within rightventricle 28 and right atrium 26, respectively. Therapy system 70 shownin FIG. 3 may be useful for providing defibrillation and/or pacingpulses to heart 12.

FIG. 4 is a functional block diagram of one example configuration of IMD16, which includes processor 80, memory 82, stimulation generator 84,sensing module 86, telemetry module 88, and power source 90. Herein, forIMD 16, the processor 80, memory 82, stimulation generator 84, sensingmodule 86, and telemetry module 88 are collectively referred to as“control electronics.” Memory 82 includes computer-readable instructionsthat, when executed by processor 80, cause IMD 16 and processor 80 toperform various functions attributed to IMD 16 and processor 80 herein.Memory 82 may include any volatile, non-volatile, magnetic, optical, orelectrical media, such as a random access memory (RAM), read-only memory(ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM(EEPROM), flash memory, or any other digital media.

Processor 80 may include any one or more of a microprocessor, acontroller, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field-programmable gate array (FPGA), orequivalent discrete or integrated logic circuitry. In some examples,processor 80 may include multiple components, such as any combination ofone or more microprocessors, one or more controllers, one or more DSPs,one or more ASICs, or one or more FPGAs, as well as other discrete orintegrated logic circuitry. The functions attributed to processor 80herein may be embodied as software, firmware, hardware or anycombination thereof. Processor 80 controls stimulation generator 84 todeliver stimulation therapy to heart 12 according to a selected one ormore of therapy programs, which may be stored in memory 82.Specifically, processor 80 may control stimulation generator 84 todeliver electrical pulses with the amplitudes, pulse widths, frequency,or electrode polarities specified by the selected one or more therapyprograms.

Stimulation generator 84 is electrically coupled to electrodes 40, 42,44, 46, 48, 50, 58, 62, 64, 66, e.g., via conductors of the respectivelead 18, 20, 22, or, in the case of housing electrode 58, via anelectrical conductor disposed within housing 60 of IMD 16. Stimulationgenerator 84 is configured to generate and deliver electricalstimulation therapy to heart 12. For example, stimulation generator 84may deliver defibrillation shocks to heart 12 via at least twoelectrodes 58, 62, 64, 66. Stimulation generator 84 may deliver pacingpulses via electrodes 40, 44, 48 (e.g., ring electrodes) coupled toleads 18, 20, 22, respectively, and/or electrodes 42, 46, 50 (e.g.,helical electrodes) of leads 18, 20, 22, respectively. In some examples,stimulation generator 84 delivers pacing, cardioversion, ordefibrillation stimulation in the form of electrical pulses. In otherexamples, stimulation generator may deliver one or more of these typesof stimulation in the form of other signals, such as sine waves, squarewaves, or other substantially continuous time signals.

Stimulation generator 84 may include a switch module and processor 80may use the switch module to select, e.g., via a data/address bus, whichof the available electrodes are used to deliver defibrillation shocksand/or pacing pulses. The switch module may include a switch array,switch matrix, multiplexer, or any other type of switching devicesuitable to selectively couple stimulation energy to selectedelectrodes.

Sensing module 86 monitors signals from at least one of electrodes 40,42, 44, 46, 48, 50, 58, 62, 64, 66 in order to monitor electricalactivity of heart 12, e.g., via electrocardiogram (ECG) signals. Sensingmodule 86 may also include a switch module to select which of theavailable electrodes are used to sense the heart activity. In someexamples, processor 80 may select the electrodes that function as senseelectrodes via the switch module within sensing module 86, e.g., byproviding signals via a data/address bus. In some examples, sensingmodule 86 includes one or more sensing channels, each of which maycomprises an amplifier. In response to the signals from processor 80,the switch module of within sensing module 86 may couple the outputsfrom the selected electrodes to one of the sensing channels.

In some examples, one channel of sensing module 86 may include an R-waveamplifier that receives signals from electrodes 40 and 42, which areused for pacing and sensing in right ventricle 28 of heart 12. Anotherchannel may include another R-wave amplifier that receives signals fromelectrodes 44 and 46, which are used for pacing and sensing proximate toleft ventricle 32 of heart 12. In some examples, the R-wave amplifiersmay take the form of an automatic gain controlled amplifier thatprovides an adjustable sensing threshold as a function of the measuredR-wave amplitude of the heart rhythm.

In addition, in some examples, one channel of sensing module 86 mayinclude a P-wave amplifier that receives signals from electrodes 48 and50, which are used for pacing and sensing in right atrium 26 of heart12. In some examples, the P-wave amplifier may take the form of anautomatic gain controlled amplifier that provides an adjustable sensingthreshold as a function of the measured P-wave amplitude of the heartrhythm. Examples of R-wave and P-wave amplifiers are described in U.S.Pat. No. 5,117,824 (Keimel et al.). Other amplifiers may also be used.Furthermore, in some examples, one or more of the sensing channels ofsensing module 86 may be selectively coupled to housing electrode 58, orelongated electrodes 62, 64, 66, with or instead of one or more ofelectrodes 40, 42, 44, 46, 48, 50, e.g., for unipolar sensing of R-wavesor P-waves in any of chambers 26, 28, 32 of heart 12.

In some examples, sensing module 86 includes a channel that comprises anamplifier with a relatively wider pass band than the R-wave or P-waveamplifiers. Signals from the selected sensing electrodes that areselected for coupling to this wide-band amplifier may be provided to amultiplexer, and thereafter converted to multi-bit digital signals by ananalog-to-digital converter for storage in memory 82 as an electrogram(EGM). In some examples, the storage of such EGMs in memory 82 may beunder the control of a direct memory access circuit. Processor 80 mayemploy digital signal analysis techniques to characterize the digitizedsignals stored in memory 82 to detect and classify the patient's heartrhythm from the electrical signals. Processor 80 may detect and classifythe heart rhythm of patient 14 by employing any of the numerous signalprocessing methodologies known in the art.

If IMD 16 is configured to generate and deliver pacing pulses to heart12, processor 80 may include pacer timing and control module, which maybe embodied as hardware, firmware, software, or any combination thereof.The pacer timing and control module may comprise a dedicated hardwarecircuit, such as an ASIC, separate from other processor 80 components,such as a microprocessor, or a software module executed by a componentof processor 80, which may be a microprocessor or ASIC. The pacer timingand control module may include programmable counters which control thebasic time intervals associated with DDD, VVI, DVI, VDD, AAI, DDI, DDDR,VVIR, DVIR, VDDR, AAIR, DDIR, and other modes of single and dual chamberpacing. In the aforementioned pacing modes, “D” may indicate dualchamber, “V” may indicate a ventricle, “I” may indicate inhibited pacing(e.g., no pacing), and “A” may indicate an atrium. The first letter inthe pacing mode may indicate the chamber that is paced, the secondletter may indicate the chamber in which an electrical signal is sensed,and the third letter may indicate the chamber in which the response tosensing is provided.

Intervals defined by the pacer timing and control module withinprocessor 80 may include atrial and ventricular pacing escape intervals,refractory periods during which sensed P-waves and R-waves areineffective to restart timing of the escape intervals, and the pulsewidths of the pacing pulses. As another example, the pace timing andcontrol module may define a blanking period, and provide signals fromsensing module 86 to blank one or more channels, e.g., amplifiers, for aperiod during and after delivery of electrical stimulation to heart 12.The durations of these intervals may be determined by processor 80 inresponse to stored data in memory 82. The pacer timing and controlmodule of processor 80 may also determine the amplitude of the cardiacpacing pulses.

During pacing, escape interval counters within the pacer timing/controlmodule of processor 80 may be reset upon sensing of R-waves and P-waves.Stimulation generator 84 may include pacer output circuits that arecoupled, e.g., selectively by a switching module, to any combination ofelectrodes 40, 42, 44, 46, 48, 50, 58, 62, 66 appropriate for deliveryof a bipolar or unipolar pacing pulse to one of the chambers of heart12. Processor 80 may reset the escape interval counters upon thegeneration of pacing pulses by stimulation generator 84, and therebycontrol the basic timing of cardiac pacing functions, includinganti-tachyarrhythmia pacing.

The value of the count present in the escape interval counters whenreset by sensed R-waves and P-waves may be used by processor 80 tomeasure the durations of R-R intervals, P-P intervals, P-R intervals andR-P intervals, which are measurements that may be stored in memory 82.Processor 80 may use the count in the interval counters to detect atachyarrhythmia event, such as ventricular fibrillation event orventricular tachycardia event. Upon detecting a threshold number oftachyarrhythmia events, processor 80 may identify the presence of atachyarrhythmia episode, such as a ventricular fibrillation episode, aventricular tachycardia episode, or a non-sustained tachycardia (NST)episode.

In some examples, processor 80 may operate as an interrupt drivendevice, and is responsive to interrupts from pacer timing and controlmodule, where the interrupts may correspond to the occurrences of sensedP-waves and R-waves and the generation of cardiac pacing pulses. Anynecessary mathematical calculations to be performed by processor 80 andany updating of the values or intervals controlled by the pacer timingand control module of processor 80 may take place following suchinterrupts. A portion of memory 82 may be configured as a plurality ofrecirculating buffers, capable of holding series of measured intervals,which may be analyzed by processor 80 in response to the occurrence of apace or sense interrupt to determine whether the patient's heart 12 ispresently exhibiting atrial or ventricular tachyarrhythmia.

In some examples, an arrhythmia detection method may include anysuitable tachyarrhythmia detection algorithms. In one example, processor80 may utilize all or a subset of the rule-based detection methodsdescribed in U.S. Pat. No. 5,545,186 (Olson et al.) or in U.S. Pat. No.5,755,736 (Gillberg et al.). Other arrhythmia detection methodologiesmay also be employed by processor 80 in other examples.

In the examples described herein, processor 80 may identify the presenceof an atrial or ventricular tachyarrhythmia episode by detecting aseries of tachyarrhythmia events (e.g., R-R or P-P intervals having aduration less than or equal to a threshold) of an average rateindicative of tachyarrhythmia or an unbroken series of short R-R or P-Pintervals. The thresholds for determining the R-R or P-P interval thatindicates a tachyarrhythmia event may be stored within memory 82 of IMD16. In addition, the number of tachyarrhythmia events that are detectedto confirm the presence of a tachyarrhythmia episode may be stored as anumber of intervals to detect (NID) threshold value in memory 82. Insome examples, processor 80 may also identify the presence of thetachyarrhythmia episode by detecting a variable coupling intervalbetween the R-waves of the heart signal. For example, if the intervalbetween successive tachyarrhythmia events varies by a particularpercentage or the differences between the coupling intervals are higherthan a given threshold over a predetermined number of successive cycles,processor 80 may determine that the tachyarrhythmia is present.

If processor 80 detects an atrial or ventricular tachyarrhythmia basedon signals from sensing module 86, and an anti-tachyarrhythmia pacingregimen is desired, timing intervals for controlling the generation ofanti-tachyarrhythmia pacing therapies by stimulation generator 84 may beloaded by processor 80 into the pacer timing and control module tocontrol the operation of the escape interval counters therein and todefine refractory periods during which detection of R-waves and P-wavesis ineffective to restart the escape interval counters.

If IMD 16 is configured to generate and deliver defibrillation shocks toheart 12, stimulation generator 84 may include a high voltage chargecircuit and a high voltage output circuit. In the event that generationof a cardioversion or defibrillation shock is required, processor 80 mayemploy the escape interval counter to control timing of suchcardioversion and defibrillation shocks, as well as associatedrefractory periods. In response to the detection of atrial orventricular fibrillation or tachyarrhythmia requiring a cardioversionpulse, processor 80 may activate a cardioversion/defibrillation controlmodule, which may, like pacer timing and control module, be a hardwarecomponent of processor 80 and/or a firmware or software module executedby one or more hardware components of processor 80. Thecardioversion/defibrillation control module may initiate charging of thehigh voltage capacitors of the high voltage charge circuit ofstimulation generator 84 under control of a high voltage chargingcontrol line.

Processor 80 may monitor the voltage on the high voltage capacitor,e.g., via a voltage charging and potential (VCAP) line. In response tothe voltage on the high voltage capacitor reaching a predetermined valueset by processor 80, processor 80 may generate a logic signal thatterminates charging. Thereafter, timing of the delivery of thedefibrillation or cardioversion pulse by stimulation generator 84 iscontrolled by the cardioversion/defibrillation control module ofprocessor 80. Following delivery of the fibrillation or tachycardiatherapy, processor 80 may return stimulation generator 84 to a cardiacpacing function and await the next successive interrupt due to pacing orthe occurrence of a sensed atrial or ventricular depolarization.

Stimulation generator 84 may deliver cardioversion or defibrillationshocks with the aid of an output circuit that determines whether amonophasic or biphasic pulse is delivered, whether housing electrode 58serves as cathode or anode, and which electrodes are involved indelivery of the cardioversion or defibrillation shocks. Suchfunctionality may be provided by one or more switches or a switchingmodule of stimulation generator 84.

Telemetry module 88 includes any suitable hardware, firmware, softwareor any combination thereof for communicating with another device, suchas programmer 24 (FIG. 1). Under the control of processor 80, telemetrymodule 88 may receive downlink telemetry from and send uplink telemetryto programmer 24 with the aid of an antenna, which may be internaland/or external. Processor 80 may provide the data to be uplinked toprogrammer 24 and the control signals for the telemetry circuit withintelemetry module 88, e.g., via an address/data bus. In some examples,telemetry module 88 may provide received data to processor 80 via amultiplexer.

In some examples, processor 80 may transmit atrial and ventricular heartsignals (e.g., electrocardiogram signals) produced by atrial andventricular sense amp circuits within sensing module 86 to programmer24. Programmer 24 may interrogate IMD 16 to receive the heart signals.Processor 80 may store heart signals within memory 82, and retrievestored heart signals from memory 82. Processor 80 may also generate andstore marker codes indicative of different cardiac episodes that sensingmodule 86 detects, and transmit the marker codes to programmer 24. Anexample pacemaker with marker-channel capability is described in U.S.Pat. No. 4,374,382 (Markowitz).

The various components of IMD 16 are coupled to power source 90, whichincludes a non-rechargeable (or “primary”) battery as described ingreater detail herein below.

FIG. 5 is block diagram of an example programmer 24. As shown in FIG. 5,programmer 24 includes processor 100, memory 102, user interface 104,telemetry module 106, and power source 108. Programmer 24 may be adedicated hardware device with dedicated software for programming of IMD16. Alternatively, programmer 24 may be an off-the-shelf computingdevice running an application that enables programmer 24 to program IMD16.

A user may use programmer 24 to select therapy programs (e.g., sets ofstimulation parameters), generate new therapy programs, modify therapyprograms through individual or global adjustments or transmit the newprograms to a medical device, such as IMD 16 (FIG. 1). The clinician mayinteract with programmer 24 via user interface 104, which may includedisplay to present graphical user interface to a user, and a keypad oranother mechanism for receiving input from a user.

Processor 100 can take the form one or more microprocessors, DSPs,ASICs, FPGAs, programmable logic circuitry, or the like, and thefunctions attributed to processor 100 herein may be embodied ashardware, firmware, software or any combination thereof. Memory 102 maystore instructions that cause processor 100 to provide the functionalityascribed to programmer 24 herein, and information used by processor 100to provide the functionality ascribed to programmer 24 herein. Memory102 may include any fixed or removable magnetic, optical, or electricalmedia, such as RAM, ROM, CD-ROM, hard or floppy magnetic disks, EEPROM,or the like. Memory 102 may also include a removable memory portion thatmay be used to provide memory updates or increases in memory capacities.A removable memory may also allow patient data to be easily transferredto another computing device, or to be removed before programmer 24 isused to program therapy for another patient. Memory 102 may also storeinformation that controls therapy delivery by IMD 16, such asstimulation parameter values.

Programmer 24 may communicate wirelessly with IMD 16, such as using RFcommunication or proximal inductive interaction. This wirelesscommunication is possible through the use of telemetry module 106, whichmay be coupled to an internal antenna or an external antenna. Anexternal antenna that is coupled to programmer 24 may correspond to theprogramming head that may be placed over heart 12, as described abovewith reference to FIG. 1. Telemetry module 106 may be similar totelemetry module 88 of IMD 16 (FIG. 4).

Telemetry module 106 may also be configured to communicate with anothercomputing device via wireless communication techniques, or directcommunication through a wired connection. Examples of local wirelesscommunication techniques that may be employed to facilitatecommunication between programmer 24 and another computing device includeRF communication according to the 802.11 or Bluetooth specificationsets, infrared communication, e.g., according to the IrDA standard, orother standard or proprietary telemetry protocols. In this manner, otherexternal devices may be capable of communicating with programmer 24without needing to establish a secure wireless connection.

Power source 108 delivers operating power to the components ofprogrammer 24. Power source 108 may include a battery and a powergeneration circuit to produce the operating power. In some embodiments,the battery may be rechargeable to allow extended operation. Rechargingmay be accomplished by electrically coupling power source 108 to acradle or plug that is connected to an alternating current (AC) outlet.In addition or alternatively, recharging may be accomplished throughproximal inductive interaction between an external charger and aninductive charging coil within programmer 24. In other embodiments,traditional primary batteries (e.g., nickel cadmium or lithium ionbatteries) may be used. In addition, programmer 24 may be directlycoupled to an alternating current outlet to power programmer 24. Powersource 108 may include circuitry to monitor power remaining within abattery. In this manner, user interface 104 may provide a currentbattery level indicator or low battery level indicator when the batteryneeds to be replaced or recharged. In some cases, power source 108 maybe capable of estimating the remaining time of operation using thecurrent battery.

Referring again to FIG. 4, processor 80 of IMD 16 may detect atachyarrhythmia episode, such as a ventricular fibrillation, ventriculartachycardia, fast ventricular tachyarrhythmia episode, or a NST episode,based on electrocardiographic activity of heart 12 that is monitored viasensing module 86. For example, sensing module 86, with the aid of atleast some of the electrodes 40, 42, 44, 46, 48, 50, 58, 62, 64, 66(shown in FIGS. 1-2), may generate an electrocardiogram (ECG) orelectrogram (EGM) signal that indicates the electrocardiographicactivity. Alternatively, sensing module 86 may be coupled to senseelectrodes that are separate from the stimulation electrodes thatdeliver electrical stimulation to heart 12 (shown in FIGS. 1-3), and maybe coupled to one or more different leads than leads 18, 20, 22 (shownin FIGS. 1-2). The ECG signal may be indicative of the depolarization ofheart 12.

For example, as previously described, in some examples, processor 80 mayidentify the presence of a tachyarrhythmia episode by detecting athreshold number of tachyarrhythmia events (e.g., R-R or P-P intervalshaving a duration less than or equal to a threshold). In some examples,processor 80 may also identify the presence of the tachyarrhythmiaepisode by detecting a variable coupling interval between the R-waves ofthe heart signal.

FIG. 6 is a block diagram illustrating a system 190 that includes anexternal device 192, such as a server, and one or more computing devices194A-194N that are coupled to IMD 16 and programmer 24 shown in FIG. 1via a network 196, according to one embodiment. In this embodiment, MD16 uses its telemetry module 88 to communicate with programmer 24 via afirst wireless connection, and to communicate with an access point 198via a second wireless connection. In the example of FIG. 6, access point198, programmer 24, external device 192, and computing devices 194A-194Nare interconnected, and able to communicate with each other, throughnetwork 196. In some cases, one or more of access point 198, programmer24, external device 192, and computing devices 194A-194N may be coupledto network 196 through one or more wireless connections. IMD 16,programmer 24, external device 192, and computing devices 194A-194N mayeach comprise one or more processors, such as one or moremicroprocessors, DSPs, ASICs, FPGAs, programmable logic circuitry, orthe like, that may perform various functions and operations, such asthose described herein.

Access point 198 may comprise a device that connects to network 196 viaany of a variety of connections, such as telephone dial-up, digitalsubscriber line (DSL), or cable modem connections. In other examples,access point 198 may be coupled to network 196 through different formsof connections, including wired or wireless connections. In someexamples, access point 198 may communicate with programmer 24 and/or IMD16. Access point 198 may be co-located with patient 14 (e.g., within thesame room or within the same site as patient 14) or may be remotelylocated from patient 14. For example, access point 198 may be a homemonitor that is located in the patient's home or is portable forcarrying with patient 14.

During operation, IMD 16 may collect, measure, and store various formsof diagnostic data. In certain cases, IMD 16 may directly analyzecollected diagnostic data and generate any corresponding reports oralerts. In some cases, however, IMD 16 may send diagnostic data toprogrammer 24, access point 198, and/or external device 192, eitherwirelessly or via access point 198 and network 196, for remoteprocessing and analysis.

In some cases, IMD 16 and/or programmer 24 may combine all of thediagnostic data into a single displayable lead integrity report, whichmay be displayed on programmer 24. The lead integrity report containsdiagnostic information concerning one or more electrode leads that arecoupled to IMD 16, such as leads 18, 20, or 22. A clinician or othertrained professional may review and/or annotate the lead integrityreport, and possibly identify any lead-related conditions.

In another example, IMD 16 may provide external device 192 withcollected diagnostic data via access point 198 and network 196. Externaldevice 192 includes one or more processors 200. In some cases, externaldevice 192 may request such data, and in some cases, IMD 16 mayautomatically or periodically provide such data to external device 192.Upon receipt of the diagnostic data via input/output device 202,external device 192 is capable of analyzing the data and generatingreports or alerts upon determination that there may be a possiblecondition with one or more of leads 18, 20, and 22. For example, one ormore of leads 18, 20, and 22 may experience a condition related to alead fracture or an insulation breach.

In one embodiment, external device 192 may combine the diagnostic datainto a lead integrity report. One or more of computing devices 194A-194Nmay access the report through network 196 and display the report tousers of computing devices 194A-194N. In some cases, external device 192may automatically send the report via input/output device 202 to one ormore of computing devices 194A-194N as an alert, such as an audio orvisual alert. In some cases, external device 192 may send the report toanother device, such as programmer 24, either automatically or uponrequest. In some cases, external device 192 may display the report to auser via input/output device 196.

In one embodiment, external device 192 may comprise a secure storagesite for diagnostic information that has been collected from IMD 16and/or programmer 24. In this embodiment, network 196 may comprise anInternet network, and trained professionals, such as clinicians, may usecomputing devices 194A-194N to securely access stored diagnostic data onexternal device 192. For example, the trained professionals may need toenter usernames and passwords to access the stored information onexternal device 192. In one embodiment, external device 192 may be aCareLink server provided by Medtronic, Inc., of Minneapolis, Minn.

The techniques described in this disclosure, including those attributedto IMD 16, programmer 24, or various constituent components, may beimplemented, at least in part, in hardware, software, firmware or anycombination thereof. For example, various aspects of the techniques maybe implemented within one or more processors, including one or moremicroprocessors, DSPs, ASICs, FPGAs, or any other equivalent integratedor discrete logic circuitry, as well as any combinations of suchcomponents, embodied in programmers, such as physician or patientprogrammers, stimulators, image processing devices or other devices. Theterm “processor” or “processing circuitry” may generally refer to any ofthe foregoing logic circuitry, alone or in combination with other logiccircuitry, or any other equivalent circuitry.

Such hardware, software, firmware may be implemented within the samedevice or within separate devices to support the various operations andfunctions described in this disclosure. In addition, any of thedescribed units, modules or components may be implemented together orseparately as discrete but interoperable logic devices. Depiction ofdifferent features as modules or units is intended to highlightdifferent functional aspects and does not necessarily imply that suchmodules or units must be realized by separate hardware or softwarecomponents. Rather, functionality associated with one or more modules orunits may be performed by separate hardware or software components, orintegrated within common or separate hardware or software components.

When implemented in software, the functionality ascribed to the systems,devices and techniques described in this disclosure may be embodied asinstructions on a computer-readable medium such as RAM, ROM, NVRAM,EEPROM, FLASH memory, magnetic data storage media, optical data storagemedia, or the like. The instructions may be executed by one or moreprocessors to support one or more aspects of the functionality describedin this disclosure.

FIG. 7A is a conceptual diagram illustrating an exemplary implantablemedical device system (e.g., a therapy system) 110 that provideselectrical stimulation therapy to patient 112. Therapy system 110includes IMD 114 and medical lead 116. In the example shown in FIG. 7A,IMD 114 provides deep brain stimulation (DBS) to brain 118 of patient112. Lead 116 is implanted within patient 112 such that one or moreelectrodes 117 carried by lead 116 are located proximate to a targettissue site within brain 118. IMD 114 provides electrical stimulation toregions within brain 118 in order to manage a condition of patient 112,such as to mitigate the severity or duration of the patient condition.In some examples, more than one lead 116 may be implanted within brain118 of patient 112 to provide stimulation to multiple anatomical regionsof brain 118. As shown in FIG. 7A, system 110 may also include aprogrammer 120, which may be a handheld device, portable computer, orworkstation that provides a user interface to a clinician or other user.The clinician may interact with the user interface to programstimulation parameters.

DBS may be used to treat various patient conditions, such as, but notlimited to, seizure disorders (e.g., epilepsy), pain, migraineheadaches, psychiatric disorders (e.g., mood or anxiety disorders),movement disorders (e.g., essential tremor or Parkinson's disease),Huntington's disease, and other neurodegenerative disorders. Theanatomic region within patient 112 that serves as the target tissue sitefor stimulation delivered by IMD 114 may be selected based on thepatient condition. For example, stimulating an anatomical region, suchas the substantia nigra, in brain 118 may reduce the number andmagnitude of tremors experienced by patient 112. Other target anatomicalregions for treatment of movement disorders may include the subthalamicnucleus, globus pallidus interna, ventral intermediate, and zonainserta. Anatomical regions such as these may be targeted by theclinician during implantation of lead 116. In other words, the clinicianmay attempt to position lead 116 within or proximate to these targetregions within brain 118.

DBS lead 116 may include one or more electrodes 117 placed along thelongitudinal axis of lead 116. In some examples, electrodes 117 mayinclude at least one ring electrode that resides along the entirecircumference of lead 116. Electrical current from the ring electrodespropagates in all directions from the active electrode. The resultingstimulation field reaches anatomical regions of brain 118 within acertain distance in all directions. The stimulation field may reach thetarget anatomical region, but the stimulation field may also affectnon-target anatomical regions and produce unwanted side effects. Inother examples, lead 116 may include a complex electrode array geometrythat includes segmented or partial ring electrodes in addition to orinstead of ring electrodes. The electrodes in a complex electrode arraymay be located at different axial and angular positions around thecircumference of the lead, as well as at different longitudinalpositions (i.e., along the longitudinal axis of lead 116). A complexelectrode array geometry may be useful for customizing the stimulationfield and provide improved therapy while decreasing side effects. Forexample, with a complex electrode array, electrodes may be selectedalong the longitudinal axis of lead 116 as well as along thecircumference of lead 116. Activating selective electrodes of lead 116can produce customizable stimulation fields that may be directed to aparticular side of lead 116 in order to isolate the stimulation fieldaround the target anatomical region of brain 118. In this manner,specific electrodes of the complex electrode array geometry may beselected to produce a stimulation field at desired portions of thecircumference instead of always producing a stimulation field around theentire circumference of the lead, as with some ring electrodes.

Producing irregular stimulation fields with a lead 116 with a complexelectrode geometry may allow therapy system 110 to more effectivelytreat certain anatomical regions of brain 118. In some cases, a therapysystem 110 including lead 116 with a complex electrode array may alsohelp reduce or eliminate side effects from more spherical stimulationfields produced by a conventional array of ring electrodes. The centerof the stimulation field may be moved away from lead 116 to avoidunwanted stimulation or compensate for inaccurately placed leads.

In the example shown in FIG. 7A, lead 116 is coupled to IMD 114 viaconnector 122, which defines a plurality of electrical contacts forelectrically coupling electrodes 117 to a stimulation generator withinIMD 114. Lead 116 is indirectly coupled to connector 122 with the aid oflead extension 124. In some examples, lead 116 may be directly coupledto connector 122 without the aid of extension 124.

In this example, programmer 120 is an external computing device that isconfigured to wirelessly communicate with IMD 114. For example,programmer 120 may be a clinician programmer that the clinician uses tocommunicate with IMD 114. Alternatively, programmer 120 may be a patientprogrammer that allows patient 112 to view and modify therapyparameters. The clinician programmer may include more programmingfeatures than the patient programmer. In other words, more complex orsensitive tasks may only be allowed by the clinician programmer toprevent patient 112 from making undesired changes to IMD 114.

Programmer 120 may be a hand-held computing device that includes adisplay viewable by the user and a user input mechanism that can be usedto provide input to programmer 120. For example, programmer 120 mayinclude a small display screen (e.g., a liquid crystal display or alight emitting diode display) that presents information to the user. Inaddition, programmer 120 may include a keypad, buttons, a peripheralpointing device, touch screen or another input mechanism that allows theuser to navigate though the user interface of programmer 120 and provideinput.

If programmer 120 includes buttons and a keypad, the buttons may bededicated to performing a certain function, i.e., a power button, or thebuttons and the keypad may be soft keys that change in functiondepending upon the section of the user interface currently viewed by theuser. Alternatively, the screen (not shown) of programmer 120 may be atouch screen that allows the user to provide input directly to the userinterface shown on the display. The user may use a stylus or theirfinger to provide input to the display.

In other examples, rather than being a handheld computing device or adedicated computing device, programmer 120 may be a larger workstationor a separate application within another multi-function device. Forexample, the multi-function device may be a cellular phone or personaldigital assistant that can be configured to an application to simulateprogrammer 120. Alternatively, a notebook computer, tablet computer, orother personal computer may enter an application to become programmer120 with a wireless adapter connected to the personal computer forcommunicating with IMD 114.

When programmer 120 is configured for use by the clinician, programmer120 may be used to transmit initial programming information to IMD 114.This initial information may include system 110 hardware informationsuch as the type of lead 116, the position of lead 116 within patient112, the therapy parameter values of therapy programs stored within IMD114 or within programmer 120, and any other information the cliniciandesires to program into IMD 114.

With the aid of programmer 120 or another computing device, a clinicianmay select values for therapy parameters for controlling therapydelivery by therapy system 110. The values for the therapy parametersmay be organized into a group of parameter values referred to as a“therapy program” or “therapy parameter set.” “Therapy program” and“therapy parameter set” are used interchangeably herein. In the case ofelectrical stimulation, the therapy parameters may include an electrodecombination, and an amplitude, which may be a current or voltageamplitude, and, if IMD 114 delivers electrical pulses, a pulse width,and a pulse rate for stimulation signals to be delivered to the patient.An electrode combination may include a selected subset of one or moreelectrodes 117 located on one or more implantable leads 116 coupled toIMD 114. The electrode combination may also refer to the polarities ofthe electrodes in the selected subset. By selecting particular electrodecombinations, a clinician may target particular anatomic structureswithin brain 118 of patient 112. In addition, by selecting values foramplitude, pulse width, and pulse rate, the physician can attempt togenerate an efficacious therapy for patient 112 that is delivered viathe selected electrode subset. Due to physiological diversity, conditiondifferences, and inaccuracies in lead placement, the parameters maygreatly vary between patients.

During a programming session, the clinician may determine one or moretherapy programs that may provide effective therapy to patient 112.Patient 112 may provide feedback to the clinician as to the efficacy ofthe specific program being evaluated. Once the clinician has identifiedone or more programs that may be beneficial to patient 112, patient 112may continue the evaluation process and determine which program bestalleviates the condition of patient 112 or otherwise providesefficacious therapy to patient 112. Programmer 120 may assist theclinician in the creation/identification of therapy programs byproviding a methodical system of identifying potentially beneficialtherapy parameters.

In some examples, the clinician may select therapy parameters using thetechniques described in U.S. Patent Application Publication Nos.2007/0203546 (Stone et al.) and 2007/0203541 (Goetz et al.), whichdescribe programming systems and methods that support the programming ofstimulation parameters with a therapy system 110 including a lead 116,which may include a complex electrode array geometry.

In accordance with techniques described in U.S. Patent ApplicationPublication No. 2007/0203546, a user interface of programmer 120 maydisplay a representation of the anatomical regions of patient 112, suchas anatomical regions of brain 118. The three-dimensional (3D) space ofthe anatomical regions may be displayed as multiple two-dimensional (2D)views or a 3D visualization environment. Lead 116 may also berepresented on the display of the user interface, positioned accordingto the actual implantation location by the clinician or directly from animage taken of the lead within brain 118. The clinician may interactwith the user interface of programmer 120 to manually select and programcertain electrodes of lead 116, select an electrode level of the leadand adjust the resulting stimulation field with the anatomical regionsas guides, or defining one or more stimulation fields that only affectanatomical regions of interest. Once the clinician has defined the oneor more stimulation fields, system 110 automatically generates thestimulation parameter values associated with each of the stimulationfields and transmits the parameter values to IMD 114. The stimulationparameter values may be stored as therapy programs within a memory ofIMD 114 and/or a memory within programmer 120.

In accordance with techniques described in U.S. Patent ApplicationPublication No. 2007/0203541, programmer 120 may present a userinterface that displays electrodes of lead 116 and enables a user toselect individual electrodes to form an electrode combination andspecify parameters for stimulation delivered via the electrodecombination. In accordance with other techniques described in U.S.Patent Application Publication No. 2007/0203541, programmer 120 maypresent a user interface to a user that enables the user to manipulate arepresentation of an electrical stimulation field (i.e., one type oftherapy field) produced by a selected electrode combination. A processorwithin programmer 120 may then select the appropriate electrodecombination, electrode polarities, amplitudes, pulse widths, and pulserates of electrical stimulation sufficient to support the fieldmanipulation operations inputted by the user into programmer 120. Thatis, programmer 120 may automatically generate a therapy program thatbest fits a stimulation field created by a user via a user interface ofprogrammer 120.

Programmer 120 may also be configured for use by patient 112. Whenconfigured as the patient programmer, programmer 120 may have limitedfunctionality in order to prevent patient 112 from altering criticalfunctions or applications that may be harmful to patient 112. In thismanner, programmer 120 may only allow patient 112 to adjust certaintherapy parameters or set an available range of values for a particulartherapy parameter. Programmer 120 may also provide an indication topatient 112 when therapy is being delivered or when the power sourcewithin programmer 120 or IMD 114 need to be replaced or recharged.

Whether programmer 120 is configured for clinician or patient use,programmer 120 may communicate with IMD 114 or any other computingdevice via wireless communication. Programmer 120, for example, maycommunicate via wireless communication with IMD 114 using radiofrequency (RF) telemetry techniques known in the art. Programmer 120 mayalso communicate with another programmer or computing device via a wiredor wireless connection using any of a variety of local wirelesscommunication techniques, such as RF communication according to the802.11 or Bluetooth specification sets, infrared communication accordingto the IRDA specification set, or other standard or proprietarytelemetry protocols. Programmer 120 may also communicate with anotherprogramming or computing device via exchange of removable media, such asmagnetic or optical disks, or memory cards or sticks. Further,programmer 120 may communicate with IMD 114 and other another programmervia remote telemetry techniques known in the art, communicating via alocal area network (LAN), wide area network (WAN), public switchedtelephone network (PSTN), or cellular telephone network, for example.

In other applications of therapy system 110, the target therapy deliverysite within patient 112 may be a location proximate to a spinal cord orsacral nerves (e.g., the S2, S3 or S4 sacral nerves) in patient 112 orany other suitable nerve, organ, muscle or muscle group in patient 112,which may be selected based on, for example, a patient condition. Forexample, therapy system 110 may be used to deliver an electricalstimulation to tissue proximate to a pudendal nerve, a perineal nerve orother areas of the nervous system, in which cases, lead 116 would beimplanted and substantially fixed proximate to the respective nerve. Asfurther examples, an electrical stimulation system may be positioned todeliver a stimulation to help manage peripheral neuropathy orpost-operative pain mitigation, ilioinguinal nerve stimulation,intercostal nerve stimulation, gastric stimulation for the treatment ofgastric mobility disorders and obesity, muscle stimulation, formitigation of other peripheral and localized pain (e.g., leg pain orback pain). In addition, although a single lead 116 is shown in FIG. 7A,in some therapy systems, two or more leads may be electrically coupledto IMD 114.

FIG. 7B is a conceptual diagram of another example of an implantablemedical device system (e.g., therapy system) 130 that deliverselectrical stimulation to target tissue sites proximate to spinal cord132 of patient 112. Therapy system 130 includes IMD 114, which iscoupled to leads 134, 136 via connector block 122. Leads 134, 136 eachinclude an array of electrodes 135, 137, respectively. IMD 114 maydeliver stimulation to patient 112 via a combination of electrodes 135,137. Electrodes 135, 137 may each be any suitable type of electrode,such as a ring electrode, partial ring electrode or segmented electrode.

In some examples, the array of electrodes 135, 137 may also include atleast one sense electrode that senses a physiological parameter ofpatient 112, such as, but not limited to, a heart rate, respirationrate, respiratory volume, core temperature, muscular activity,electromyogram (EMG), an electroencephalogram (EEG), anelectrocardiogram (ECG) or galvanic skin response. Therapy systems 110,130 may also include sensor 126 (shown in FIG. 7A, not shown in FIG. 7B)in addition to or instead of sense electrodes on the leads 116, 134,136. Sensor 126 may be a sensor configured to detect an activity level,posture, or another physiological parameter of patient 112. For example,sensor 126 may generate a signal that changes as a function of thephysiological parameter of patient 112. Sensor 126 may be implanted orexternal to patient 112, and may be wirelessly coupled to IMD 114 or viaa lead, such as leads 116, 134, 136, or another lead. For example,sensor 126 may be implanted within patient 112 at a different site thanIMD 114 or sensor 126 may be external. In some examples, sensor 126 maybe incorporated into a common housing with IMD 114. In addition to, orinstead of, being coupled to IMD 114, in some cases, sensor 126 may bewirelessly coupled to programmer 120 or coupled to programmer 120 by awired connection.

In the example shown in FIG. 7B, leads 134, 136 are positioned todeliver bilateral stimulation to patient 112, i.e., stimulation signalsare delivered to target tissue sites on opposite sides of a midline ofpatient 112. The midline may generally be defined along spinal cord 132.Just as with therapy system 110, a clinician may generate one or moretherapy programs for therapy system 130 by selecting values for one ormore types of therapy parameters that provide efficacious therapy topatient 112 with the aid of programmer 120 or another computing device.The therapy parameters may include, for example, a combination of theelectrodes of leads 134 and/or 136, the voltage or current amplitude,pulse width, and frequency of stimulation.

FIG. 8 is a functional block diagram of an exemplary IMD 114. IMD 114includes a processor 140, memory 142, stimulation generator 144,switching module 146, telemetry module 148, and power source 150.Herein, for IMD 114, the processor 140, memory 142, stimulationgenerator 144, switching module 146, and telemetry module 148 arecollectively referred to as “control electronics.” As shown in FIG. 8,stimulation generator 144 is coupled to leads 134, 136, for example, viaswitching module 146. Alternatively, stimulation generator 144 may becoupled to a single lead (e.g., as shown in FIG. 7A) or more than threeleads directly or indirectly (e.g., via a lead extension, such as abifurcating lead extension that may electrically and mechanically coupleto two leads) as needed to provide stimulation therapy to patient 112.

In the example illustrated in FIG. 8, lead 134 includes electrodes135A-135D (collectively referred to as “electrodes 135”) and lead 136includes electrodes 137A-137D (collectively referred to as “electrodes137”). Electrodes 135, 137 may be ring electrodes. In other examples,electrodes 135, 137 may be arranged in a complex electrode array thatincludes multiple non-contiguous electrodes at different angularpositions about the outer circumference of the respective lead 134, 136,as well as different levels of electrodes spaced along a longitudinalaxis of the respective lead 134, 136. The configuration, type, andnumber of electrodes 135, 137 illustrated in FIG. 8 are merelyexemplary. In other examples, IMD 114 may be coupled to any suitablenumber of leads with any suitable number and configuration ofelectrodes.

Memory 142 includes computer-readable instructions that, when executedby processor 140, cause IMD 114 to perform various functions. Memory 142may include any volatile, non-volatile, magnetic, optical, or electricalmedia, such as a random access memory (RAM), read-only memory (ROM),non-volatile RAM (NVRAM), electrically-erasable programmable ROM(EEPROM), flash memory, or any other digital media. Memory 142 mayinclude programs 152, program groups 154, and operating instructions 156in separate memories within memory 142 or separate areas within memory142. Each program 152 defines a particular program of therapy in termsof respective values for electrical stimulation parameters, such aselectrode combination, electrode polarity, current or voltage amplitude,pulse width and pulse rate. A program group 154 defines a group ofprograms that may be delivered together on an overlapping ornon-overlapping basis. Operating instructions 156 guide generaloperation of IMD 114 under control of processor 140, and may includeinstructions for measuring, for example, the impedance of electrodes135, 137 and/or determining the distance between electrodes 135, 137.

Stimulation generator 144 produces stimulation signals, which may bepulses as primarily described herein, or continuous time signals, suchas sine waves, for delivery to patient 112 via selected combinations ofelectrodes 135, 137. Processor 140 controls stimulation generator 144according to programs 152 and program groups 154 stored in memory 142 toapply particular stimulation parameter values specified by one or moreof programs, such as amplitude, pulse width, and pulse rate. Processor140 may include a microprocessor, a controller, a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield-programmable gate array (FPGA), or equivalent discrete orintegrated digital or analog logic circuitry, and the functionsattributed to processor 140 herein may be embodied as software,firmware, hardware or any combination thereof.

Processor 140 also controls switching module 146 to apply thestimulation signals generated by stimulation generator 144 to selectedcombinations of electrodes 135, 137. In particular, switching module 146couples stimulation signals to selected conductors within leads 134, 136which, in turn, deliver the stimulation signals across selectedelectrodes 135, 137. Switching module 146 may be a switch array, switchmatrix, multiplexer, or any other type of switching device suitable toselectively couple stimulation energy to selected electrodes. Hence,stimulation generator 144 is coupled to electrodes 135, 137 viaswitching module 146 and conductors within leads 134, 136. In someexamples, IMD 114 does not include switching module 146.

Stimulation generator 144 may be a single- or multi-channel stimulationgenerator. In particular, stimulation generator 144 may be capable ofdelivering, a single stimulation pulse, multiple stimulation pulses, ora continuous signal at a given time via a single electrode combinationor multiple stimulation pulses at a given time via multiple electrodecombinations. In some examples, however, stimulation generator 144 andswitching module 146 may be configured to deliver multiple channels on atime-interleaved basis. In this case, switching module 146 serves totime division multiplex the output of stimulation generator 144 acrossdifferent electrode combinations at different times to deliver multipleprograms or channels of stimulation energy to patient 112.

Telemetry module 148 supports wireless communication between IMD 114 andan external programmer 120 (not shown in FIG. 8) or another computingdevice under the control of processor 140. Processor 140 of IMD 114 mayreceive, as updates to programs, values for various stimulationparameters such as amplitude and electrode combination, from programmer120 via telemetry interface (i.e., module) 148. The updates to thetherapy programs may be stored within programs 152 portion of memory142.

The various components of IMD 114 are coupled to power source 150, whichincludes a non-rechargeable (i.e., primary) battery as described herein.

FIG. 9 is a functional block diagram of an example of programmer 120. Asshown in FIG. 9, external programmer 120 includes processor 160, memory162, user interface 164, telemetry module 166 (i.e., telemetryinterface), and power source 168. A clinician or another user mayinteract with programmer 120 to generate and/or select therapy programsfor delivery in IMD 114. For example, in some examples, programmer 120may allow a clinician to define stimulation fields and generateappropriate stimulation parameter values. Processor 160 may storestimulation parameter values as one or more therapy programs in memory162. Processor 160 may send programs to IMD 114 via telemetry module 166to control stimulation automatically and/or as directed by the user.

As previously described, programmer 120 may be a handheld computingdevice, a workstation or another dedicated or multifunction computingdevice. For example, programmer 120 may be a general purpose computingdevice (e.g., a personal computer, personal digital assistant (PDA),cell phone, and so forth) or may be a computing device dedicated to, forexample, programming IMD 114. Programmer 120 may be one of a clinicianprogrammer or a patient programmer in some examples, i.e., theprogrammer may be configured for use depending on the intended user. Aclinician programmer may include more functionality than the patientprogrammer. For example, a clinician programmer may include a morefeatured user interface that allows a clinician to download usage andstatus information from IMD 114, and allows the clinician to controlaspects of IMD 114 not accessible by a patient programmer example ofprogrammer 120.

A user, either a clinician or patient 112, may interact with processor160 through user interface 164. User interface 164 may include adisplay, such as a liquid crystal display (LCD), light-emitting diode(LED) display, or other screen, to present information related tostimulation therapy, and buttons or a pad to provide input to programmer120. In examples where user interface 164 requires a 3D environment, theuser interface may support 3D environments such as a holographicdisplay, a stereoscopic display, an autostereoscopic display, ahead-mounted 3D display, or any other display that is capable ofpresenting a 3D image to the user. Buttons may include an on/off switch,plus and minus buttons to zoom in or out or navigate through options, aselect button to pick or store an input, and pointing device, e.g. amouse, trackball, or stylus. Other input devices may be a wheel toscroll through options or a touch pad to move a pointing device on thedisplay. In some examples, the display may be a touch screen thatenables the user to select options directly from the display screen.

Processor 160 processes instructions from memory 162 and may store userinput received through user interface 164 into memory 162 whenappropriate for the current therapy. In addition, processor 160 providesand supports any of the functionality described herein with respect toeach example of user interface 164. Processor 160 may comprise any oneor more of a microprocessor, DSP, ASIC, FPGA, or other digital logiccircuitry, and the functions attributed to processor 160 herein may beembodied as software, firmware, hardware or any combination thereof.

Memory 162 may include instructions for operating user interface 164,telemetry module 166 and managing power source 168. Memory 162 may storeprogram instructions that, when executed by processor 160, causeprocessor 160 and programmer 120 to provide the functionality ascribedto them herein. Memory 162 also includes instructions for generatingtherapy programs, such as instructions for determining stimulationparameters for achieving a user-selected stimulation fields orinstructions for determining a resulting stimulation field fromuser-selected stimulation parameters. Memory 162 may include any one ormore of a RAM, ROM, EEPROM, flash memory, or the like.

Wireless telemetry in programmer 120 may be accomplished by radiofrequency (RF) communication or proximal inductive interaction ofprogrammer 120 with IMD 114. This wireless communication is possiblethrough the use of telemetry module 166. Accordingly, telemetry module166 may include circuitry known in the art for such communication.

Power source 168 delivers operating power to the components ofprogrammer 120. Power source 168 may include a battery and a powergeneration circuit to produce the operating power. In some examples, thebattery may be rechargeable to allow extended operation. Recharging maybe accomplished through proximal inductive interaction, or electricalcontact with circuitry of a base or recharging station. In otherexamples, primary (i.e., non-rechargeable) batteries may be used. Inaddition, programmer 120 may be directly coupled to an alternatingcurrent source, such would be the case with some computing devices, suchas personal computers.

The techniques described in this disclosure, including those attributedto IMD 114, programmer 120, or various constituent components, may beimplemented, at least in part, in hardware, software, firmware or anycombination thereof. For example, various aspects of the techniques maybe implemented within one or more processors, including one or moremicroprocessors, DSPs, ASICs, FPGAs, or any other equivalent integratedor discrete logic circuitry, as well as any combinations of suchcomponents, embodied in programmers, such as physician or patientprogrammers, stimulators, image processing devices or other devices. Theterm “processor” or “processing circuitry” may generally refer to any ofthe foregoing logic circuitry, alone or in combination with other logiccircuitry, or any other equivalent circuitry.

Such hardware, software, firmware may be implemented within the samedevice or within separate devices to support the various operations andfunctions described in this disclosure. In addition, any of thedescribed units, modules or components may be implemented together orseparately as discrete but interoperable logic devices. Depiction ofdifferent features as modules or units is intended to highlightdifferent functional aspects and does not necessarily imply that suchmodules or units must be realized by separate hardware or softwarecomponents. Rather, functionality associated with one or more modules orunits may be performed by separate hardware or software components, orintegrated within common or separate hardware or software components.

When implemented in software, the functionality ascribed to the systems,devices and techniques described in this disclosure may be embodied asinstructions on a computer-readable medium such as RAM, ROM, NVRAM,EEPROM, FLASH memory, magnetic data storage media, optical data storagemedia, or the like. The instructions may be executed by one or moreprocessors to support one or more aspects of the functionality describedin this disclosure.

Exemplary Implantable Medical Device Batteries

Although certain materials described herein are rechargeable,implantable medical device batteries of the present disclosure arepreferably primary (i.e., non-rechargeable) batteries. A typical batteryincludes a case, a liner, and an electrode assembly. The liner surroundsthe electrode assembly to prevent the electrode assembly from contactingthe inside of the case. The electrode assembly includes one or moreelectrochemical cells, wherein each electrochemical cell includes ananode and a cathode with one or more separators therebetween, and anelectrolyte to facilitate ionic transport and form a conductive pathwaybetween the anode and cathode. Although the following descriptionfocuses on ICDs, one of skill in the art would appreciate that theseconcepts can also apply to other IMDs.

In a more detailed description, FIG. 10 depicts an IMD 210 that includesa case or housing 250, a control module 252, a battery 254, and one ormore capacitor(s) 256. Control module 252 controls one or more sensingand/or stimulation processes from IMD 210 via leads (not shown). Battery254 includes an insulator 258 disposed therearound. Battery 254 chargescapacitor(s) 256 and powers control module 252. For example, in animplantable cardioverter defibrillator, the control module includescontrol electronics for delivering therapy and/or monitoringphysiological signals, and includes a processor, memory, a stimulationgenerator that generates at least one of cardiac pacing pulses,defibrillation shocks, and cardioversion shocks, and a sensing modulefor monitoring a patient's heart rhythm. The capacitors are typicallyhigh voltage capacitors (e.g., typically greater than 600 volts forICDs, although this can vary and is generally known to one of skill inthe art what is suitable for various IMD applications). The ICD alsoincludes an implantable medical device battery operably connected to thecontrol electronics to deliver power to the control electronics andoperably connected to the capacitors to charge the capacitors.

FIGS. 11 and 12 depict details of an exemplary battery 254. Battery 254,which as shown includes one cell, includes a case 270, an anode 272,separators 274, a cathode 276, a liquid electrolyte 278, and afeed-through terminal 280. Cathode 276 is wound in a plurality of turns,with anode 272 interposed between the turns of the cathode winding.Separator 274 insulates anode 272 from cathode 276 windings. Case 270contains the liquid electrolyte 278 to create a conductive path betweenanode 272 and cathode 276. Electrolyte 278 serves as a medium formigration of ions between anode 272 and cathode 276 during discharge ofthe cell.

Exemplary ways to construct battery 254 are described, for example, inU.S. Pat. Nos. 5,439,760 (Howard et al.) and 6,017,656 (Crespi et al.),and U.S. Patent Application Publication No. 2006/0166078A1 (Chen etal.).

Typical commercial IMD batteries cannot meet the power and capacityrequirements of either conventional IMDs or those in development in lessthan about 6.5 cubic centimeters (cc). Thus, there is a need forbatteries with smaller volumes while maintaining relatively high powercapability and capacity, which are provided herein in certainembodiments.

In the design of an IMD battery, the desired longevity of the device andaverage current drains are used to determine the required batterycapacity. The energy density of the electrode materials can then be usedto determine the volume of battery anode and cathode required. Thedesired capacitor charge time, charge energy, and charge circuitefficiency are used to determine the required battery power. The ratecapability (power per unit area) of the electrode materials can then beused to determine the surface area required for the anode and cathode.The required surface area will then determine how much inert material(such as current collector and separator) is needed, and therefore thetotal cell volume. So, generally, a smaller battery (and, hence, asmaller IMD) can be produced by reducing IMD current drain, improvingcharging circuit efficiency, using an electrode set with greater energydensity, and using an electrode set with greater rate capability.

It has proven difficult, however, to balance battery power, capacity,and volume in an IMD battery having a practical longevity. For example,an IMD battery volume can be reduced by reducing the anode and cathodethicknesses, as described herein; however, while this alone may producepowers of a level suitable for use, the capacity may be too low.Alternatively, an IMD battery volume can be reduced by reducing theactive area of the electrodes as well as the amount of inert materialwithin the cell; however, while this alone may produce capacities of alevel suitable for use, the powers may be too low. Certain aspects ofthe present disclosure have overcome the significant challengesassociated with designing a battery having relatively small volume withboth relatively high power and relatively high capacity for a relativelylong useful life. Thus, certain embodiments of the present disclosureare directed to a battery of relatively small volume but of relativelyhigh power (reported as therapeutic power) and relatively high capacity(reported as capacity density).

Significantly, in certain embodiments, IMD batteries of the presentdisclosure have a longevity (i.e., “useful life”) of conventional IMDbatteries, which is on the order of years. Preferably, IMD batteries ofthe present disclosure have a longevity of at least 5 years. Morepreferably, the useful life is at least 7 years. Even more preferably,the useful life is at least 9 years. Typically, the useful life is nogreater than 15 years.

In certain embodiments, IMD batteries of the present disclosure have atotal volume of no greater than 6.0 cubic centimeters (“cc” or cm³). Insome embodiments, the total volume is no greater than 5.5 cc, no greaterthan 5.0 cc, no greater than 4.5 cc, or no greater than 4.0 cc.Preferably, the battery total volume is at least 3.0 cc. The term “totalvolume” is the total overall volume of the battery, not the volume ofany individual cell (unless the battery includes only one cell). An IMDbattery of the present disclosure may include one or more individualcells, each of which includes one cathode (e.g., “one” cathode caninclude an assembly of individual cathode plates electrically connectedas in a stacked plate construction), one anode (e.g., “one” anode caninclude an assembly of individual anode plates electrically connected asin a stacked plate construction), one or more separator(s), and anelectrolyte. Thus, the summation of the volumes of the individualelectrochemical cells is the total volume of the battery. Typically, IMDbatteries of the present disclosure include one cell, although this isnot required for all embodiments of the disclosure.

Herein, IMD batteries are preferably described in terms of “therapeuticcapacity density” and “therapeutic power.” These are not to be mistakenwith conventional terms like “capacity” or “capacity density” or “power”but are more useful in understanding the benefits of the presentdisclosure. This is because conventional terms may include differingfractions of capacity that are not usable for the application, makingdesign and comparison of batteries difficult.

Briefly, “therapeutic capacity density” refers to the battery'stherapeutic capacity delivered over the useful life of the batterydivided by the battery volume, wherein “therapeutic capacity” refers tothe total capacity delivered until the cell power (average voltage timesthe average current) decreases to a specified wattage (the wattage whenthe average voltage is 1.6 V. How these values are determined is shownin the Examples Section.

Briefly, the term “therapeutic power” refers to the amount of cell power(as defined above) a battery delivers for every joule of therapeuticenergy delivered, calculated as the amount of energy delivered by astimulation generator to a patient in a single stimulation event (e.g.,one pacing shock, one defibrillation shock, or one cardioversion shock).How these values are determined is shown in the Examples Section.

Significantly, preferred small IMD batteries of the present disclosurepossess a therapeutic power of at least 0.11 Watt (W) for every joule oftherapeutic energy delivered over the useful life of the battery. Insome embodiments, the therapeutic power is at least 0.14 W, at least0.17 W, or at least 0.20 W, for every joule of therapeutic energydelivered over the useful life of the battery. Typically, for suchembodiments, the therapeutic power is no greater than 0.5 W for everyjoule of therapeutic energy delivered over the useful life of thebattery.

Significantly, preferred small IMD batteries of the present disclosurepossess a therapeutic capacity density of at least 0.08 ampere hours percubic centimeter (Ah/cc). In some embodiments, the therapeutic capacitydensity is at least 0.10 Ah/cc, at least 0.13 Ah/cc, at least 0.15Ah/cc, at least 0.18 Ah/cc, or at least 0.20 Ah/cc. Typically, for suchembodiments, the therapeutic capacity density is no greater than 0.5Ah/cc.

For certain embodiments, the anode to cathode capacity ratio ispreferably within a range of 0.6:1 to 1.5:1. For certain embodiments,anodes of IMD batteries of the present disclosure have a total uniformthickness determined by the anode to cathode capacity ratio and thecathode capacity. For example, typical thicknesses are less than 0.015inch, and at least 0.002 inch.

Significantly, for certain embodiments, cathodes of IMD batteries of thepresent disclosure have a total uniform thickness that is thinner thanthat of cathodes of conventional IMD batteries of similar power andcapacity.

The term “total uniform thickness” in the context of an electrode refersto the total overall thickness of the electrode, not the thickness ofany individual layer (e.g., an extruded or coated layer of cathodematerial or a layer of metal foil used as a current collector). Thisthickness is uniform along its length (excluding any uncoated areas suchas tabs or edges on individual electrode plates and the portions of theelectrode forming the outermost wraps or plates), with tolerances of nomore than ±0.003 inch (3 mil), and preferably no more than ±0.001 inch(1 mil).

For certain embodiments, the cathodes of IMD batteries of the presentdisclosure have a total uniform thickness of less than 0.014 inch. Incertain embodiments, the total uniform thickness of a cathode is nogreater than 0.013 inch, no greater than 0.012 inch, no greater than0.011 inch, no greater than 0.010 inch, no greater than 0.009 inch, nogreater than 0.008 inch, or no greater than 0.007 inch. The totaluniform thickness of a cathode of an IMD battery of the presentdisclosure is typically at least 0.004 inch.

Typical thicknesses of commercial IMD battery cathodes having the powerand capacity requirements of the batteries of the present disclosure are0.014 inch and greater. Although certain reported cathodes are preparedfrom layers of very thin material, thereby resulting in a totalthickness that may be thinner than 0.014 inch, such batteries would nothave the small volume, high therapeutic power, and high capacity densityof the batteries of the present disclosure; hence no commerciallyavailable IMD batteries include cathodes as thin as those of the presentdisclosure.

Cathodes and anodes of IMD batteries of the present disclosure havesurface areas sufficient to provide the desired power. Preferably, thesurface areas are independently at least 60 square centimeters (cm²). Insome embodiments, the surface areas of the cathode and anode areindependently at least 70 cm², at least 80 cm², or at least 90 cm².Typically, the surface areas of the cathode and anode are independentlyno greater than 110 cm². The surface area of a cathode may be the sameor different than that of the anode.

Cathodes and anodes of IMD batteries of the present disclosure may havea variety of shapes. Typically, they are in the form of plates or coils.For example, an electrode (cathode or anode) is typically a thincoating, sheet, or foil of the active material disposed on one or bothmajor surfaces of a thin film of a current collector (e.g., nickel,copper, aluminum, titanium, gold, platinum, tantalum, stainless steel,or another conductive metal that is corrosion-resistant when associatedwith the active material). An anode, cathode, and separator can becombined in a variety of structures, including, for example, spiralwound form, stacked plate form, or serpentine form, as disclosed, forexample, in U.S. Pat. No. 5,439,760 (Howard et al.) and U.S. PatentApplication Publication No. 2006/0166078 (Chen et al.).

Preferably, each electrode includes one current collector (i.e., onesingle layer of a current collector). That is, for certain preferredembodiments, for a coiled electrode, each of the cathode and anodeincludes one current collector. For a stacked plate electrode assembly,however, in any one electrode plate, there is one current collector orone single layer of a current collector, which are electricallyconnected to each other to form a “single” current collector for thecombined set of electrode plates.

If a stacked plate electrode is used, an individual electrode is formedof individual electrode plates that are electrically connected on eachside. Thus, the “surface area” referred to above in the context of anelectrode refers to the total area of the electrode (e.g., the area ofthe active cathode material, which excludes any areas such as tabs oredges on individual cathode plates that do not include active cathodematerial), which is the summation of the surface areas of eachindividual electrode plate, excluding any area that is not opposing theother electrode. Thus, the surface area of a stacked plate electrodedoes not include the outermost surface of the two electrode plates ateach end of the stack.

Typically, anodes of IMD batteries, such as anode 272, are formed of anactive material that includes lithium, which can be in metallic or ionicfaun (typically, metallic faun). It may also include other materials,particularly those selected from Group IA, IIA, or 111B of the periodictable of elements (e.g., sodium, potassium, etc.). The anode can includemixtures, alloys (e.g., Li—Al alloy), or intermetallic compounds (e.g.,Li—Si, Li—B, Li—Si—B etc.) of the elements of Groups IA, IIA, or 111B ofthe periodic table with each other or with other elements of theperiodic table.

Cathodes of IMD batteries of the present disclosure, such as cathode276, are formed of an active material that includes one or more metaloxides. Such metal oxides may include one or more different metals(e.g., the active material can include mixed metal oxides). The cathodematerial can also include two or more different materials, which can bein admixture or in layers, or both.

Exemplary metal oxides for use in the cathode active material includeMnO₂, V₆O₁₃, silver vanadium oxide (e.g., AgV₂O₅, Ag₂V₄O₁₁,Ag_(0.35)V₂O_(5.8), Ag_(0.74)V₂O_(5.37), AgV₄O_(5.5)), copper silvervanadium oxide (e.g., Cu_(0.16)Ag_(0/67)V₂O_(5.5) orCu_(0.5)Ag_(0.5)V₂O_(5.75)), V₂O₅, copper oxide, copper vanadium oxide,or combinations thereof. Combinations of such materials can be used ifdesired. Preferred metal oxides are the various materials that includesilver and vanadium oxide, referred to generally as “silver vanadiumoxide” or “SVO.” SVO is capable of being synthesized using a variety ofmethods. Methods of synthesis generally fall within two categories,depending on the type of chemical reaction that produces the SVO. SVOcan be synthesized using a decomposition reaction, resulting indecomposition-produced SVO (DSVO). Alternatively, SVO can be synthesizedusing a combination reaction, resulting in combination-produced SVO(CSVO). Regardless of how it is made, SVO can be formed in a variety ofdifferent structural phases (e.g., β, γ, ∈) and have a variety ofdifferent crystalline forms. A particularly preferred metal oxide isAg₂V₄O₁₁, which is prepared by the addition reaction described in U.S.Pat. No. 5,221,453 (Crespi).

Preferably, cathode material of IMD batteries of the present disclosurealso includes a second active material that is of a higher energydensity and a lower rate capability than the metal oxide active material(i.e., the first active material) described above. Typically andpreferably, this second active material is carbon monofluoride, althoughother materials such as Ag₂O, Ag₂O₂, CuF, Ag₂CrO₄, MnO₂, and even SVOcan be used. Combinations of such materials can be used if desired.Carbon monofluoride, often referred to as carbon fluoride, polycarbonmonofluoride, CF_(x) or graphite fluoride is a solid, structural,non-stoichiometric fluorocarbon of empirical formula CF_(x), wherein xis 0.01 to 1.9, preferably 0.1 to 1.5, and more preferably 1.1. Onecommercial form of carbon monofluoride is (CF_(x))_(n), where 0<x<1.25(and n is the number of monomer units in the polymer, which can varywidely).

Generally, production of CF_(x) involves an exemplary chemical reactionsuch as:

F₂+(x+y+z)C→xCF_(1.1) yC+z(CF_(n≧2))

where x, y, and z are numerical values that may be positive integers orpositive rational numbers. In this reaction, fluorine and carbon reactto form CF_(1.1). Unreacted carbon and impurities are by-products of thechemical reaction, which are preferably minimized during production ofCF_(x). It is desirable to achieve a weight percentage of fluorinegreater than or equal to 61% in CF_(x) while reducing impurities.Preferably, greater than or equal to 63% or 65% of fluorine exists inthe CF_(x). Purity, crystallinity, and particle shape, particularly ofthe carbon precursor, are also properties to consider in the selectionof carbon monofluoride. This is described in greater detail in U.S.Patent Application Publication No. 2007/0178381 (Howard et al.).Therein, fibrous CF_(x) materials are described, which are particularlyadvantageous.

A particularly preferred cathode material is silver vanadium oxide usedin combination with carbon monofluoride, preferably as a mixture. TheCF_(x):SVO capacity ratio is preferably within a range of 10:1 to 1:1.The CF_(x):SVO stoichiometric ratio is preferably within a range of 2:1to 4:1 (electrochemical equivalents). There are various forms of silvervanadium oxide and carbon monofluoride, such as those described in U.S.Pat. Nos. 5,180,642 (Weiss et al.) and 6,783,888 (Gan et al.), and U.S.Patent Application Publication No. 2007/0178381 (Howard et al.).

The particle sizes and shapes are also characteristics of the cathodematerials to be considered. This is particularly true in obtaining thethin, yet effective, coatings of the cathode material on the currentcollector. For example, desirably, particles of the cathode material areless than 20% of the electrode thickness. The particle size is typicallyno greater than 100 microns, although even smaller particles (e.g., nogreater than 20 microns) can be more desirable in certain situations.

Although uniformly or regularly shaped (e.g., spherical) particles aredesired for ease of coating, mechanical integrity of the cathode,enhanced compressibility (providing increased cell capacity), rod-shaped(i.e., fibrous or filamentous) particles may contribute to higher power.For certain embodiments of the present invention, the cathode materialincludes fibrous particles, and for certain embodiments, the cathodematerial includes a mixture of fibrous particles with irregularly shapedagglomerates of needle-shaped particles.

The cathode material typically also includes a conductivity enhancer anda binder. The conductivity enhancer is typically a conductive carbon,such as carbon black, acetylene black, and/or graphite, although othermetallic powders can be used such as aluminum, titanium, nickel, andstainless steel. Various combinations of such conductivity enhancers canbe used if desired. The amount of conductive enhancer is typically atleast 1 wt-%, and typically no more than 10 wt-%, based on the totalweight of the dry cathode mix (without solvent).

The binder can be carboxy methyl cellulose (CMC), styrene-butadienerubber (SBR), polyvinylidene difluoride (PVDF), polytetrafluoroethylene(PTFE), or combinations thereof. Preferred binders are SBR and PVDF. Amore preferred binder is SBR. The amount of binder is typically at least1 wt-%, and typically no more than 5 wt-%, based on the total weight ofthe dry cathode mix (without solvent).

Such binders can be used in a battery of relatively small volume but ofrelatively high power (reported as therapeutic power) and relativelyhigh capacity (reported as capacity density), but this is not arequirement. Using these polymers, particularly the SBR, the activeingredients can be increased to greater than 92 wt-%, making thecathode/battery more energy dense. The cathode mixture can be slurrycoated, as discussed in greater detail below, allowing for much thinnerlayers, which is more cost effective, and provides higher yields. Thus,for certain embodiments of the present disclosure, a non-rechargeablebattery is provided that includes: an anode; a cathode comprising abinder comprising styrene-butadiene rubber; a separator between theanode and the cathode; and an electrolyte contacting the anode, thecathode, and the separator.

The current collectors used in the electrodes of IMD batteries of thepresent disclosure are of the type used conventionally. Generally, theyare metal films or foils, such as aluminum, titanium, nickel, copper, oranother conductive metal that is corrosion-resistant when associatedwith the active anode material. They may be primed or unprimed. They maybe perforated or not. The thicknesses of the current collectors aretypically at least 0.0001 inch, and more often at least 0.003 inch. Thethicknesses of the current collectors are typically no greater than 0.01inch (e.g., a titanium current collector is typically 0.005 inch thickto handle the current load without becoming excessively hot), and oftenno greater than 0.001 inch (e.g., an aluminum current collector can beas thin as 20 microns (0.0008 inch)). The separators used inelectrochemical cells of IMD batteries of the present disclosure areselected to electrically insulate the anode from the cathode.Conventional materials can be used. The material is generally wettableby the cell electrolyte, sufficiently porous to allow the electrolyte toflow through separator material, and maintains physical and chemicalintegrity within the cell during operation. Examples of suitableseparator materials include, but are not limited to, fluoropolymericfabrics, polytetrafluoroethylene (PTFE), ceramics, non-woven glass,glass fiber material, polypropylene, and polyethylene. For example, theseparator can include macroporous polyethylene (PE) or polypropylene(PP) and/or a layer of non-woven polypropylene or polyethylene laminatedto it. As described in U.S. Patent Application Publication No.2006/0166078 (Chen et al.), a separator can consist of three layers, forexample, having a polyethylene layer sandwiched between two layers ofpolypropylene. The polyethylene layer has a lower melting point than thepolypropylene layers and provides a shut down mechanism in case of cellover heating.

The electrolyte includes a liquid organic electrolyte, which typicallyincludes an organic solvent in combination with an ionizing solute. Theorganic solvent can be, for example, diethylcarbonate,dimethylcarbonate, dipropylcarbonate, diisopropylcarbonate,di-tert-butylcarbonate, dibutylcarbonate, diphenylcarbonate,dicyclopentylcarbonate, ethylenecarbonate, butylenecarbonate,3-methyl-2-oxazolidone, sulfolane, tetrahydrofuran (THF),methyl-substituted tetrahydrofuran, 1,3-dioxolane, propylene carbonate(PC), ethylene carbonate, gamma-butyrolactone, ethylene glycol sulfite,dimethylsulfite, dimethyl sulfoxide, 1,2-dimethoxyethane, dimethylisoxazole, dioxane, ethyl methyl carbonate, methyl formate, diglyme,glyme, acetonitrile, N-methyl-2-pyrrolidone (NMP), solvents of the typedisclosed in U.S. Pat. No. 6,017,656 (Crespi et al.), or the like, ormixtures thereof. The ionizing solute can be a simple or soluble salt ormixtures thereof, for example, an alkali metal salt (e.g., LiBF₄,LiAsF₆, LiPF₆, LiClO₄, LiN(SO₂CF₃)₂, LiC(SO₂CF₃)₃, LiSbF₆, LiO₂,LiAlCl₄, LiGaCl₄, LiSCN, LiO₃SCF₃, LiC₆F₅SO₃, LiO₂CCF₃, LiSO₆F,LiB(C₆H₅)₄, LiCF₃SO₃, and mixtures thereof), which will produce anionically conductive solution when dissolved in one or more solvents.For example, the electrolyte can include a lithium salt (e.g., 1.0MLiClO₄ or LiPF₆ or LiAsF₆) in a 50/50 mixture of propylene carbonate and1,2-dimethoxyethane. A preferred electrolyte is 1.0M LiAsF₆ in a mixtureof 50 vol-% propylene carbonate (PC) and 50 vol % 1,2-dimethoxyethane(DME).

Preferred Process of Making Cathodes for Batteries

Conventional methods of making IMD batteries, particularly cathodes forIMD batteries, are limited in their ability to make cathodes having thetotal uniform thicknesses described herein without sacrificing function,such as power and capacity, of the battery. For example, for designsabove 6 cc and up to 9 cc of high-rate batteries, the cathode powder istypically pressed into a Ti grid, that is then wound together withlithium foil electrically-isolated by a porous membrane. To supply therequired power, the double-sided area of the cathode approaches 90 cm².This powder dispensing cathode technology generally limits the availablecapacity of 90 cm² batteries to be 850 mAh or greater.

Although such powder dispensing cathode technology can be used incertain situations to prepare cathodes for IMD batteries of the presentdisclosure (e.g., some of the larger volume batteries), in certainembodiments, the present disclosure provides a more generally effectivemethod of forming a cathode that overcomes many of the problems of thepowder dispensing technology. The preferred method described hereinprovides primary high-rate batteries of 6 cc and smaller with high powerand high capacity capabilities. Although this method is described forcoating the cathodes for use in an IMD battery, it could also apply tocoating cathodes for use in other batteries. Also, this method can beused in making cathodes for batteries of other sizes, powers,capacities, etc. than those described herein.

This method involves coating a slurry that includes the components ofthe cathode material, such as an active cathode material (e.g.,SVO/CF_(x) mixture), binder (e.g., PVDF, CMC, SBR, or combinationsthereof), and conductivity enhancer (carbon black, acetylene black,and/or graphite), which can optionally be combined and mixed with adispersant and/or thickener in a solvent. The materials are typicallycombined in a high-shear mixer (e.g., a centrifugal mixer) and/orhigh-speed mixer, with or without mixing media (e.g., 21-mm×21-mm,cylindrically shaped, ceramic media).

The components of the cathode material are typically combined with asolvent and dispersant and/or thickener in amounts to provide thedesired viscosity suitable for the desired coating method. The solventcan be any of a wide variety of organic solvents (e.g.,N-methylpyrrolidone (NMP), methyl ethyl ketone), water, or a combinationthereof. The thickener/dispersant can be any of a wide variety ofmaterials, such as CMC, guar gum, xanthum gum, polyethylene glycol, andcombinations thereof. If PVDF is used as the binder, NMP is typicallyused as the solvent. If SBR is used as the binder, water is typicallyused as the solvent. Also, from a practical processing point, CMC isused with the SBR to better disperse the SBR.

The amounts of the solvent, dispersant, and/or thickener relative to theother components can vary depending on the desired viscosity. The amountof solvent can vary widely, but is typically at least 30 wt-%, andtypically no more than 60 wt-%, based on the total weight of the slurry.The amount of dispersant and/or thickener can vary widely, but istypically no more than 4 wt-%, based on the total weight of the slurry.

The mixing conditions (e.g., time, temperature, velocity of mixing) aresufficient to form a homogeneous mixture without any non-wetted clumpsof dry material. These conditions can vary and depend on theconcentrations of the cathode materials, but can be readily determinedby one of skill in the art.

Preferably, during mixing, the temperature of the slurry is controlledso it does not exceed levels where oxidation of components could occur.Also, it is controlled to limit evaporation of the solvent. Furthermore,the temperature of the resulting slurry affects the viscosity. Thus, itis desirable to control the temperature during both mixing and coating.

The desired viscosity of the slurry depends on the type of coatingmethod used (e.g., knife over blade coating, knife over roll coating,doctor blade coating, slot die coating, ink-jet coating (e.g., asdescribed in International Patent Application Publication No. WO2009/035488) (Nielsen et al.), etc.), the thickness of the coatingdesired, the concentrations of the components remaining in the coatedcathode material, etc. The static viscosity of a suitable slurry istypically at least 70,000 centipoise (cP), and typically no more than150,000 cP, for appropriate leveling and to avoid sagging or running.

The coating slurry, however, is a non-Newtonian fluid. Thus, theviscosity of the slurry will change as a function of flow rate (e.g.,the viscosity drops under shear). Desirably, the dynamic viscosity issuch that the value of “n” in the equation of (Visc₀)_(x)(ShearRater)^(n-1) is 0.3 to 0.6. When this occurs, the viscosity drops enoughunder shear to effectively pump the slurry, and the cross-web control ofthe coated material is maintained (e.g., such that deposition (mg/cm²)is substantially constant cross-web, and there are good “clean” edgesformed upon coating the material).

This slurry coating method results in coating chemistries of controlledthicknesses. To provide smaller batteries with the volume of interest,the amount of cathode material deposited using this slurry coatingmethod is preferably within a range of 16 mg/cm² to 35 mg/cm², dependingon the desired power and capacity

Upon slurry coating, the mixture is dried to remove substantially allthe solvent. Typically, drying of the slurry coated cathode materialoccurs by heating it up to a temperature of 60° C. to 100° C. for water,or 60° C. to 120° C. for NMP, optionally under vacuum or a nitrogenatmosphere, or it can be allowed to air dry at room temperature.

After being dried, the coated material can be compressed to obtain thedesired porosity, packing density, and thickness of the cathodematerial. The amount of compression can be determined by one of skill inthe art. Typically, pressures of 20,000 psi to 45,000 psi can be used.

EXEMPLARY EMBODIMENTS OF THE DISCLOSURE

The following outlines exemplary embodiments of the present disclosure,which are also described in Attorney Docket Nos. 134.03980101(P0031258.01) and 134.04140101 (P0031060.00), each of which is filed oneven date herewith.

1. An implantable cardioverter defibrillator device comprising:

control electronics for delivering therapy and/or monitoringphysiological signals, the control electronics comprising:

-   -   a processor;    -   memory;    -   a stimulation generator that generates at least one of cardiac        pacing pulses, defibrillation shocks, and cardioversion shocks;        and    -   a sensing module for monitoring a patient's heart rhythm;

one or more defibrillator capacitors; and

an implantable medical device battery operably connected to the controlelectronics to deliver power to the control electronics, and operablyconnected to the capacitors to charge the capacitors; wherein thebattery has a total volume of no greater than 6.0 cc, the batterycomprising:

-   -   an anode comprising lithium;    -   a cathode having a total uniform thickness of less than 0.014        inch;    -   a separator between the anode and the cathode; and    -   an electrolyte contacting the anode, the cathode, and the        separator;    -   wherein the cathode material comprises a metal oxide;

wherein the battery has a therapeutic power of at least 0.11 W for everyjoule of therapeutic energy delivered over the useful life of thebattery, and a therapeutic capacity density of at least 0.08 Ah/cc.

2. An implantable medical device comprising:

control electronics for delivering therapy and/or monitoringphysiological signals, the control electronics comprising:

-   -   a processor; and    -   memory; and

an implantable medical device battery operably connected to the controlelectronics to deliver power to the control electronics; wherein thebattery has a total volume of no greater than 6.0 cc, the batterycomprising:

-   -   an anode comprising lithium;    -   a cathode having a total uniform thickness of less than 0.014        inch;    -   a separator between the anode and the cathode; and    -   an electrolyte contacting the anode, the cathode, and the        separator;    -   wherein the cathode material comprises a metal oxide;

wherein the battery has a therapeutic power of at least 0.11 W for everyjoule of therapeutic energy delivered over the useful life of thebattery, and a therapeutic capacity density of at least 0.08 Ah/cc.

3. The implantable device of embodiment 1 or embodiment 2, wherein thebattery volume is no greater than 5.0 cc.4. The implantable device of any one of the preceding embodiments,wherein the battery volume is at least 3.0 cc.5. The implantable device of any one of the preceding embodiments,wherein the therapeutic power of the battery is at least 0.14 W forevery joule of therapeutic energy delivered over the useful life of thebattery.6. The implantable device of any one of the preceding embodiments,wherein the therapeutic capacity density of the battery is at least 0.10Ah/cc.7. The implantable device of any one of the preceding embodiments,wherein the surface area of each of the cathode and anode is at least 60cm².8. The implantable device of any one of the preceding embodiments,wherein the cathode comprises a silver vanadium oxide.9. The implantable device of any one of the preceding embodiments,wherein the cathode comprises a mixture of two or more materials.10. The implantable device of embodiment 9, wherein the cathode materialfurther comprises carbon monofluoride.11. The implantable device of any one of the preceding embodiments,wherein the cathode comprises a single current collector.12. An implantable medical device comprising:

control electronics for delivering therapy and/or monitoringphysiological signals, the control electronics comprising:

-   -   a processor; and    -   memory; and

an implantable medical device battery operably connected to the controlelectronics to deliver power to the control electronics; wherein thebattery has a total volume of no greater than 6.0 cc, the batterycomprising:

-   -   an anode comprising lithium;    -   a cathode comprising a single current collector and having a        total uniform thickness of less than 0.014 inch;    -   a separator between the anode and the cathode; and    -   an electrolyte contacting the anode, the cathode, and the        separator;    -   wherein the cathode material comprises a layer on each major        surface of the single current collector, wherein the layer        comprises a mixture comprising a metal oxide and carbon        monofluoride;

wherein the battery has a therapeutic power of at least 0.11 W for everyjoule of therapeutic energy delivered over the useful life of thebattery, and a therapeutic capacity density of at least 0.08 Ah/cc.

13. An implantable medical device system comprising:

an implantable medical device of any one of embodiments 1 through 12;and

components operably attached to the implantable medical device fordelivering therapy and/or monitoring physiological signals.

14. An implantable medical device battery comprising:

an anode comprising lithium;

a cathode having a total uniform thickness of less than 0.014 inch;wherein the cathode material comprises a metal oxide;

a separator between the anode and the cathode; and

an electrolyte contacting the anode, the cathode, and the separator;

wherein the battery has a therapeutic power of at least 0.11 W for everyjoule of therapeutic energy delivered over the useful life of thebattery, and a therapeutic capacity density of at least 0.08 Ah/cc.

15. The battery of embodiment 14, wherein the battery volume is nogreater than 5.0 cc.16. The battery of embodiment 14 or embodiment 15, wherein the batteryvolume is at least 3.0 cc.17. The battery of any one of embodiments 14 through 16, wherein thetherapeutic power of the battery is at least 0.14 W for every joule oftherapeutic energy delivered over the useful life of the battery.18. The battery of any one of embodiments 14 through 17, wherein thetherapeutic capacity density of the battery is at least 0.10 Ah/cc.19. The battery of any one of embodiments 14 through 17, wherein thesurface area of each of the cathode and anode is at least 60 cm².20. The battery of any one of embodiments 14 through 19, wherein thecathode comprises a silver vanadium oxide.21. The battery of any one of embodiments 14 through 20, wherein thecathode comprises a mixture of two or more materials.22. The battery of embodiment 21, wherein the cathode material furthercomprises carbon monofluoride.23. The battery of any one embodiments 14 through 22, wherein thecathode is prepared from a slurry coated onto a current collector.24. The battery of any one of embodiments 14 through 23, wherein thecathode material comprises a binder comprising styrene-butadiene-rubber.25. A method of making a battery, the method comprising:

preparing a cathode material slurry comprising an active cathodematerial, a binder, and a solvent;

applying the cathode material slurry to at least one major surface of acurrent collector;

removing the solvent from the coated cathode slurry material to form adry cathode coating;

compressing the dry cathode coating to reduce porosity and thickness ofthe coating;

and

combining the cathode with an anode, one or more separators, and anelectrolyte to form a battery.

26. The method of embodiment 25, wherein the battery is an implantablemedical device battery.27. The method of embodiment 25 or embodiment 26, wherein the cathodematerial slurry comprises fibrous particles.28. The method of embodiment 27, wherein the cathode material comprisesa mixture of fibrous particles with irregularly shaped agglomerates ofneedle-shaped particles29. The method of any one of embodiments 25 through 28, wherein thecathode material slurry comprises a thickener and/or dispersant.30. The method of embodiment 29, wherein the thickener and/or dispersantcomprises carboxy methyl cellulose, guar gum, xanthum gum, polyethyleneglycol, and combinations thereof.31. The method of any one of embodiments 25 through 30, wherein thebinder comprises styrene-butadiene rubber.32. The method of embodiment 31, wherein the solvent comprises water.33. The method of embodiment 31, wherein the cathode material slurrycomprises carboxy methyl cellulose.34. The method of any one of embodiments 25 through 30, wherein thebinder comprises polyvinylidene difluoride.35. The method of embodiment 34, wherein the solvent comprisesN-methyl-2-pyrrolidone.36. A non-rechargeable battery comprising:

an anode;

a cathode comprising a binder comprising styrene-butadiene rubber;

a separator between the anode and the cathode; and

an electrolyte contacting the anode, the cathode, and the separator.

37. The battery of embodiment 36, wherein the cathode comprises a silvervanadium oxide.38. The battery of embodiment 36 or 37, wherein the cathode comprises amixture of two or more materials.39. The battery of embodiment 38, wherein the cathode material furthercomprises carbon monofluoride.40. The battery of any one of embodiments 36 through 39, wherein thecathode comprises carboxy methyl cellulose.41. An implantable medical device comprising a battery of any one ofembodiments 36 through 40.42. The implantable medical device of embodiment 41 which is animplantable cardioverter defibrillator device.

EXAMPLES

Objects and advantages of this disclosure are further illustrated by thefollowing examples, but the particular materials and amounts thereofrecited in these examples, as well as other conditions and details,should not be construed to unduly limit this disclosure.

The following materials were used in the Examples:

Material Source and/or Specifications SVO Silver vanadium oxide in theform of Ag₂V₄O₁₁, manufactured according to the procedure of U.S. Pat.No. 5,221,453 (Crespi) and jet milled to a particle size of 20 micronsor less (although this is not required, rather it is done for processingpurposes in slot die coating). CFx Fibrous carbon monofluoride (62-67wt-% total fluorine, less than 0.10 wt-% free fluorine, X-raydiffraction peak ratio I (2 theta, 25.86)/I (2 theta, 28.64) of lessthan 1), ground to less than 100 micron particle size (although this isnot required, rather it is done for processing purposes in slot diecoating). Carbon Chevron Phillips Shawinigan Black ® Acetylene Black,70% black Compressed, available from Chevron Philips, The Woodlands, TX.Binder 40 wt-% in water of an SBR (a modified styrene-butadienecopolymer) emulsion (BM-400B, trade name of product manufactured by ZeonCorp., Tokyo, Japan). Disper- Daicel 2200 CMC (0.7 wt-% solution ofCarboxy Methyl sant Cellulose in water) available at Daicel ChemicalIndustries, solution Ltd., Japan. DI Deionized water water

Example 1a Preparation of Slurry with SpeedMixer and Ceramic Media

A centrifugal mixer such as a SpeedMixer DAC 150 FV, available fromFlackTek, Inc. (Landrum, S.C.) was used with mixing cups and cup holdersof various sizes. Also, two 21-mm×21-mm, cylindrically shaped, ceramicmedia were used. The SpeedMixer can make batches of slurry in amounts upto 60 grams.

To make 20 grams of slurry, 5.41 grams of SVO, 3.79 grams of CFx, and0.60 gram of carbon black were weighed and placed into a powder cup. Thepowder cup was placed in the cup holder, and then the cup holder wasplaced into the SpeedMixer. The materials were mixed by the SpeedMixerfor 30 seconds at about 2500 revolutions per minute (RPM). The powdercup then was removed from the cup holder.

The CMC dispersant was measured and added to the powder cup (9.87 gramsof Daicel 2200 CMC (0.7% solution)). Two 21-mm×21-mm ceramic cylindricalshaped media were placed into the cup with the mixture. The powder cupwas then placed into the cup holder and then the cup holder was placedinto the SpeedMixer.

The materials were mixed by the SpeedMixer for 1 minute at about 3000RPM. The slurry cup was removed from the mixer. Non-wetted clumps ofmaterial were broken up with a laboratory stirring tool (e.g., SpoonulaLab Spoon). The materials were mixed for three to five 60-secondintervals with non-wetted clumps being broken up between the 60-secondintervals.

BM-400B binder (Zeon) was weighed (0.335 gram) and added into the cup.The contents of the cup were mixed by the SpeedMixer for 30 seconds at1500 RPM.

The mixture was observed while stirring with a stirring tool to verifycomplete mixing. The mixing was repeated for three to five 30-secondintervals followed by stirring with a stirring tool, until the slurrylooked smooth. Complete wetting was visually verified.

Example 1b Preparation of Slurry with SpeedMixer Without Ceramic Media

To make 20 grams of slurry, 5.41 grams of SVO, 3.79 grams of CFx, and0.60 gram of carbon black were weighed and placed into a powder cup. Thepowder cup was placed in the cup holder, and then the cup holder wasplaced into the SpeedMixer. The materials were mixed by the SpeedMixerfor 30 seconds at about 2000 RPM. The powder cup then was removed fromthe cup holder.

Fifty percent of the CMC dispersant was added to the powder cup (50% of9.87 grams of Daicel 2200 CMC (0.7% solution)). The powder cup was thenplaced into the cup holder and then the cup holder was placed into theSpeedMixer.

The materials were mixed by the SpeedMixer for 1 minute at 3300 RPM. Theslurry cup was removed from the mixer. Non-wetted clumps were broken upwith a laboratory stirring tool (e.g., Spoonula Lab Spoon). Thematerials were mixed for three to five 60-second intervals withnon-wetted clumps being broken up between the 60-second intervals.

The mixture was observed for state of mix and to allow time for coolingif the mixture temperature was near 60° C. Another 10% of the CMCsolution was added to the mixture, when the mixture did not wet-outcompletely. While mixing in 60-second intervals, the mixture evolvedfrom a dry mix, to a paste, to a high-viscosity slurry. Mixing in60-second intervals was continued until all of the particles werewetted.

The remaining amount of CMC dispersant was added to the mixture. Thematerials were mixed by the SpeedMixer for 60 seconds at 2500 RPM. Themixture was observed and mixing in 60-second intervals was continueduntil materials were a smooth mixture by visual inspection while notexceeding 60° C.

Zeon BM-400B binder (0.335 gram) was weighed and added into the cup. Thecontents of the cup were mixed by the SpeedMixer for 30 seconds at 1500RPM. The mixture was observed while stirring with a stirring tool toverify complete mixing. The mixing was repeated for three to five more30-second intervals followed by stirring, until the slurry lookedsmooth. Complete wetting was visually verified.

Example 1c Preparation of Slurry with SpeedMixer Without Ceramic Media

To make 20 grams of slurry, 5.32 grams of SVO, 3.73 grams of CFx, and0.60 gram of carbon black were weighed and placed into a powder cup. Thepowder cup was placed in the cup holder, and then the cup holder wasplaced into the SpeedMixer. The materials were mixed by the SpeedMixerfor 30 seconds at about 2000 RPM. The powder cup then was removed fromthe cup holder.

Fifty percent of the CMC dispersant was added to the powder cup (50% of10 grams of Daicel 2200 CMC (1% solution)). The powder cup was thenplaced into the cup holder and then the cup holder was placed into theSpeedMixer.

The materials were mixed by the SpeedMixer for 1 minute at 3300 RPM. Theslurry cup was removed from the mixer. Non-wetted clumps were broken upwith a laboratory stirring tool (e.g., Spoonula Lab Spoon). Thematerials were mixed for three to five 60-second intervals withnon-wetted clumps being broken up between the 60-second intervals.

The mixture was observed for state of mix and to allow time for coolingif the mixture temperature was near 60° C. Another 10% of the CMCsolution was added to the mixture, when the mixture did not wet-outcompletely. While mixing in 60-second intervals, the mixture evolvedfrom a dry mix, to a paste, to a high-viscosity slurry. Mixing in60-second intervals was continued until all of the particles werewetted.

The remaining amount of CMC dispersant was added to the mixture. Thematerials were mixed by the SpeedMixer for 60 seconds at 2500 RPM. Themixture was observed and mixing in 60-second intervals was continueduntil materials were a smooth mixture by visual inspection while notexceeding 60° C.

Zeon BM-400B binder (0.335 gram) was weighed and added into the cup. Thecontents of the cup were mixed by the SpeedMixer for 30 seconds at 1500RPM. The mixture was observed while stirring with a stirring tool toverify complete mixing. The mixing was repeated for three to five more30-second intervals followed by stirring, until the slurry lookedsmooth. Complete wetting was visually verified.

Example 2 Coating the Current Collectors

In this Example, a knife-over-plate slurry coater, such as a P1-1210Filmcoater available from Sangyo Company, LTD, was employed along withan adjustable doctor blade.

The current collector was a 20-micrometer aluminum foil. A foil strip ofthe current collector was placed on a vacuum plate. The vacuum sourcewas activated to hold the foil in place, a parting sheet was taped to analuminum plate, and the current collector (substrate) was taped to theparting sheet. A visual inspection verified that the foil was flat onthe plate, the perimeter edges of foil were taped onto the plate.

Then, the height of the coating blade of the P1-1210 Filmcoater wasadjusted to the desired thickness of the coating. For an electrode tohave a 0.010 inch end thickness, the blade height was set at 0.018 inch.Then, a quantity of the slurry prepared as in Example 1a or 1b wasplaced on the end of the grid closest to the blade start.

Prior to each coating run the slurry was remixed for 20 seconds at 1500RPM. The coating head was run to coat at a speed of about 1 inch persecond. The tape was removed from the perimeter of the foil. Then thewet coated electrode on the aluminum plate was placed into a pre-heatedoven at 60° C. and was dried for 30 minutes.

The current collector, having a coating on one major surface, was thencoated on the opposite major surface. The height of the doctor blade wasset to deposit the same coating thickness on the second side of thecurrent collector as was deposited on the first side. A quantity ofslurry from Example 1a or 1b was deposited and coated on the second sideof the current collectors using the coating procedure described above.

Example 3 Cathode Preparation and Measurement; Cell Preparation andAssembly

With a steel rule die, cathode plates with uncoated tabs were punchedout of the coated current collectors prepared according to Example 2.Then, the punched-out cathode plates were compressed for about 10seconds at 34,000 psi (pounds per square inch) press pressure. Thecathode plates were then vacuum dried at 80° C. and about 300 mbar forover 12 hours.

Example 4 Preparation of Cell Assembly

A battery was assembled and included fifteen cathode plates preparedaccording to Example 3, fourteen two-sided anode plates, and twosingle-sided anode plates. The anode plates contained lithium metal on a0.001 inch thick (1 mil) perforated copper foil collector.

The individual cathode plates were sealed in Celgard 2320 polymerbattery separator (20 micrometer microporous trilayer membrane(PP/PE/PP), available from Celgard, LLC, Charlotte, N.C.). Theindividual anode plates were sealed in Celgard 2500 polymer batteryseparator (25 micrometer microporous membrane (PP), available fromCelgard, LLC, Charlotte, N.C.). The anode plates and cathode plates wereelectrically connected such that the batteries were made to be casenegative.

All cathode plates were incorporated into a single cell in a case havinga cover with one feedthrough hole and one hole for a fill port. Afeedthrough was welded on the inside of the case with the ferrule insidethe case. A plastic pin protector was used. A thermal cup and stackingfixture was used to stack the anode plates and cathode plates. Theinsulator cup with stacked electrodes was removed from the stackingfixture and the case liner was placed over the electrode assembly. Thestack was placed into the case, aligning the feedthrough pin with thehole in the case liner. Two feedthrough insulator discs were placed overthe feedthrough pin.

A thin strip of titanium sheet material (“jumper”) was used forinterconnecting the cathode stack to the feedthrough pin, and the holein the jumper was located over the feedthrough pin. The other end of thejumper was positioned on the tab. A foil shield was placed over the casewall next to the jumper and stack. The jumper was welded to the stack.The feedthrough pin was trimmed flush to the jumper surface. Then, thepin was welded to the jumper. A headspace cover insulator was placedover the cathode interconnect. The anode stack was resistance spotwelded to the case.

The cover was inserted into the case while ensuring that the headspacecover insulator had not rotated past the edge of the cover. The coverwas welded and dielectric withstand test was performed at 1000 volts.

The cell was filled with high rate electrolyte with the followingformulation: 1.0M LiAsF₆ in a mixture of 50 vol-% propylene carbonate(PC) and 50 vol % 1,2-dimethoxyethane (DME).

The fill port holes were welded closed. A safety holder was used as thefixture. A sleeve insulator was placed over the pin on the outside ofthe battery.

The data in Table 2 were calculated regarding the battery.

TABLE 2 Cathode utilization 0.8 Number of cathodes 15 Cathode capacitydensity (Ah/cc) 1.49 Area (total 2 sides of each plate) (cm²) 6.06 Anodecapacity density (Ah/cc) 2.06 Total separator thickness (mil) 62Cathode/Anode vol ratio (Beta) 2.94 Total effective collector thickness(mil) 28 Porosity of cathode 0.41 Thickness of an electrode pair(active) 13.7 Allowable space in thickness direction (mil) 296 Thicknessignoring lithium excess (mil) 10.7 Lithium thickness at PLF (mil) - oneach 1.5 Lithium thickness used (mil) 2.7 side Ave thickness of cathodegrid (mil) 0.8 Total lithium thickness (mil) (sum of both sides) 5.7 Avethickness of anode grid (mil) 1 Cathode thickness (mil) Active (sum ofboth sides) 8.0 Separator thickness (mil) 1 Total Cathode Thickness(mil) 8.8 Area for a 15 cathode battery of 6.06 cm2 per 90.9 cathode(cm2) Capacity for a 15 cathode battery of 6.06 cm2 per 0.62 cathode(Ah) for thickness calculation case 0.016 in cathode density as built2.01 g/cc 2.5% SBR on 1085 cover 0.016 in cathode capacity 0.44 Ah/gtheor. Based on slurry formula cup insulator 0.014 in cathode capacitydensity 0.88 Ah/cc Calculated liner 0.004 in Porosity 41% Calculatedsub-total 0.050 in theoretically dense Ah/cc 1.49 Ah/cc Calculated totalthickness 0.346 in at cathode utilization Total at cathode utilizationtotal 0.31 anode volume (cc) 0.66 0.92 cathode volume (cc) 0.92 0.65anode capacity (Ah) 1.36 0.65 cathode capacity (Ah) 0.81

Example 5 Cell Modeling

In this example, modeling of cells was performed using an electricalmodel and a mechanical model.

Mechanical modeling used design dimensions of various cell components tocalculate total cell volume and electrode surface area. The mechanicalmodeling also used known material properties of cell components, such asdensity of electrode materials, theoretical capacity of electrodematerials, porosity of the finished cathode, and the area normalizedresistance of the finished cathode.

Electrical modeling included an Ohm's Law model using cell backgroundvoltage and resistance (calculated in the mechanical model) to calculateavailable power.

In this manner, for example, capacity delivered in terms of ampere hoursper cubic centimeter was calculated given a power at 1.6 volts and amaterial. Also, for example, cell capacity density in terms of amperehours per cubic centimeter was calculated given a cell volume and at agiven therapy power at 1.6 volts.

Calculation of the Therapeutic Capacity Density of a cell is performedas follows:

The Cell Power,

CP=(V _(avg))*(i _(avg))  Eq. 1

where V_(avg) and i_(avg) are the average cell voltage and current underload, respectively, during a high power discharge for therapeuticpurposes.

The Cell Resistance,

R=(A _(elect))*(R _(norm))  Eq. 2

where A_(elect) is the electrode area and R_(norm) is the areanormalized resistance of the cell. It should be noted that R_(norm) willbe a function of depth of discharge of the cell, and may also be afunction of the time over which that discharge occurs.

At a given depth of discharge of the cell, the current supplied during ahigh power discharge is,

i _(avg)(x)=[(V _(back)(x)−V _(avg)(x))/R(x)]  Eq. 3

where V_(back)(X), V_(avg)(x), and R(x) are the background voltage,average loaded voltage, and cell resistance, respectively, at depth ofdischarge, x.

V_(back)(X) and R(x) are determined experimentally, as described inCrespi et al., “Modeling and Characterization of the Resistance ofLithium/SVO Batteries for Implantable Cardioverter Defibrillators,”Journal of the Electrochemical Society, 148, A30-A37 (2001).

The Specified Wattage occurs when V_(avg)=1.6V. The Cell Power at theSpecified Wattage is therefore

CP=1.6V*[(V _(back)(x)−1.6V)/R(x)]  Eq. 4

The average current that is observed for the Specified Wattage is

i _(avg)(x)=CP/1.6V  Eq. 5

or

i _(avg)(x)=[(V _(back)(x)−6V)/R(x)]  Eq. 6

The Therapeutic Capacity,

TC=(Q _(total))*(x)−(Q _(init))  Eq. 7

where Q_(total) is 01 the total cathode capacity, x is the % utilizationof the cathode to the point at which the Specified Wattage is met, andQ_(init) is the amount of cathode capacity removed prior to implant ofthe device.

The cathode utilization, x, of the cell at the end of the therapeuticlife of the cell is determined by:

1. Choosing the Specific Wattage that defines the end of therapeuticlife.

2. Setting the Cell Power to the Specific Wattage, and iterativelysolving Eqs. 5 and 6 for x.

The Therapeutic Capacity is then calculated from Eq. 7, and theTherapeutic Capacity Density is calculated by dividing the TherapeuticCapacity by the cell volume.

For example, for the 4.5 cc Type 2 cell in FIG. 16 [0.2 W/J], the totalcell capacity, Q_(total), is 1.08 Ah and the initial capacity, Q_(init),is 0.033 Ah. The battery area is 90.9 cm². For a 35 J therapy, theSpecified Wattage is 7 W. For the Type 2 chemistry, 7 W will be producedwith an average load voltage of 1.6V when the cathode utilization, x, is72%. At that point, the background voltage of the cell, V_(back), willbe 2.579V, and its resistance, R, will be 0.224 ohms. The TherapeuticCapacity will therefore be 0.75 Ah, and Therapeutic Capacity Density is0.17 Ah/cm³.

Therapeutic Power as depicted in FIGS. 13-16 is chosen to reflect thedesire to deliver a given amount of defibrillation therapy to thepatient in an acceptable amount of time. That time is approximately 15seconds. Beyond 15 seconds, the efficacy of the therapy is thought todecrease.

Most ICDs are designed to deliver up to 35 J of defibrillation therapyto the patient. Because there are circuit inefficiencies and deliverylosses associated with the ICD system, approximately 60 J of energy areremoved from the battery to deliver 35 J of defibrillation therapy tothe patient. (This varies up to approximately 25%, depending on thedevice and system.) Therefore, the desired minimum power of the cell isapproximately 0.11 W/J of therapeutic energy (=[60 J/35 J]/15 s).Greater power is desirable, as short therapy times are highly valued byphysicians.

The data shown in FIGS. 13-16 reflect both actual and theoretical(indicated by open data points) therapeutic cell density (Ah/cc) forvarious cell volumes (cc). The data shown in each of FIGS. 13-16 arebased on a given therapeutic power at 1.6 volts, ranging from 0.11 W/J(FIG. 13) to 0.2 W/J (FIG. 16). Each series of data labeled 1-5 in thelegend indicates one of the five different materials for coatingcathodes. The materials used are as follows: series Type “1” representsLiAgVO₂ (anode limited, as described in U.S. Pat. No. 5,458,977 (Crespiet al.)); series Type “2” represents (CF_(x)/SVO (2:1 ratio as describedin U.S. Patent Publication No. 2007/0178381 (Howard et al.)); seriesType “3” represents CF_(x)/V₆O₁₃ (2:1 ratio as described in U.S. Pat.No. 5,180,642 (Weiss et al.)); series Type “4” represents MnO₂; andseries Type “5” represents SVO (as described in U.S. Pat. No. 5,221,453(Crespi)). Actual test data is indicated with filled data points inFIGS. 13-16, whereas calculated theoretical values are indicated withopen data points.

The complete disclosures of the patents, patent documents, andpublications cited herein are incorporated by reference in theirentirety as if each were individually incorporated. Variousmodifications and alterations to this disclosure will become apparent tothose skilled in the art without departing from the scope and spirit ofthis disclosure. It should be understood that this disclosure is notintended to be unduly limited by the illustrative embodiments andexamples set forth herein and that such examples and embodiments arepresented by way of example only with the scope of the disclosureintended to be limited only by the claims set forth herein as follows.

1. A method of making a battery, the method comprising: preparing acathode material slurry comprising an active cathode material, a binder,and a solvent; applying the cathode material slurry to at least onemajor surface of a current collector; removing the solvent from thecoated cathode slurry material to form a dry cathode coating;compressing the dry cathode coating to reduce porosity and thickness ofthe coating; and combining the cathode with an anode, one or moreseparators, and an electrolyte to form a battery.
 2. The method of claim1, wherein the battery is an implantable medical device battery.
 3. Themethod of claim 1, wherein the cathode material slurry comprises fibrousparticles.
 4. The method of claim 3, wherein the cathode materialcomprises a mixture of fibrous particles with irregularly shapedagglomerates of needle-shaped particles
 5. The method of claim 1,wherein the cathode material slurry comprises a thickener and/ordispersant.
 6. The method of claim 5, wherein the thickener and/ordispersant comprises carboxy methyl cellulose, guar gum, xanthum gum,polyethylene glycol, and combinations thereof.
 7. The method of claim 1,wherein the binder comprises styrene-butadiene rubber.
 8. The method ofclaim 7, wherein the solvent comprises water.
 9. The method of claim 7,wherein the cathode material slurry comprises carboxy methyl cellulose.10. The method of claim 1, wherein the binder comprises polyvinylidenedifluoride.
 11. The method of claim 10, wherein the solvent comprisesN-methyl-2-pyrrolidone.